You aren't the first person to prioritize ventilation through the floor. I think you'd like
this and
this, blog posts by a private investigator on his ventilation solutions to keep cool. The blog in general is a pretty awesome read if you're super into stealth...I was more worried about stealth when I first started out and have begun mellowing out a bit since.
That said, rain guards on the windows can also permit cracking them open to allow some stealthy ventilation. I'm in a minivan, and when my bf got his minivan I went nuts when I saw how his sunroof can open. That's 'stealth' ceiling ventilation right there! It's in the front, though. I've since learned there's a version of Sienna minivans that comes standard with a dual moonroof--one in front, one in back--or of course you could always add one aftermarket. But if you want everything stock, well, that'd be it. My ability to stealthy crack down my side windows in the back is a small saving grace in the summer, but definitely not enough to be anywhere near comfy.
Flush mounted solar panels would still be seen from above, e.g. when parked at apartment overflow parking. But don't let that stop you if you want them!
danman81 said:
1. ... And don't carry any trailers or bikes on a bike rack and stuff like that -- use a folding bike.
Sounds like you're approaching this from a strictly work van image perspective, which is certainly one possible way to go. In my area though a bike rack with or without bikes on it is very, very common about 8 months out of the year. It isn't on cargo vans, but minivans exactly like the one I'm in? Yup. Same with rooftop cargo carriers and boxes, for that matter.
danman81 said:
9. I would even go as far as to say to keep a construction hat or safety vest with you visible from the front.
I highly recommend safety vests as part of standard vehicle emergency equipment, whether or not you flaunt the fact that you have one for 'stealth'. With my old van's super old tires, I experienced three blow-outs on the freeway, two of which were at night with very little shoulder before a concrete barrier. Each time being outside of the vehicle while checking it out or communicating with the tow truck driver I was acutely aware of how much safer I'd be if everyone whizzing by could see me.
I've mentioned elsewhere that in my preferred places to park within Seattle, which is generally apartment overflow, anything larger that a minivan stands out by its very nature of being larger than a minivan. I don't know how unique this is to my area, but if your dream stealth white cargo van came to my areas it would definitely stand out and people would notice. There aren't a lot of commercial vehicles to park next to, and those that exist either move a lot because parking in Seattle is super precious, or they're one of the few parked in residential neighborhoods where everyone knows them. This was a major factor in my switching to a minivan, and as mentioned in another thread I haven't had any break in attempts since the switch, whereas before I had several.
The most stealthy set-up I've ever noticed is a converted 'VanPool" van parked amongst a fleet of other VanPool vans in a dark corner of a parking lot. The darkness actually made it more difficult to check for silhouettes through the windows. The only thing that gave it away was they were playing music, and then I did a window check and after a good 5 minutes of looking I identified the van. To me, aside from the music, this is an example of "super stealth". Which yeah, you can do, if you know that you'd enjoy living that way. I think it's a potentially smart approach, but wouldn't fit in the places I enjoy parking.
danman81 said:
7. How you dress -- Probably the single most important thing. Don't look weird. ... Whether or not you like it, you will be profiled based on your appearance and people who look respectable are more respected than people who don't...
For me, this is simply not possible. A medical condition requires that I wear a chemical cartridge respirator unless the air is unusually clean with no people around. Most of the time I also require hiking poles to walk. I also must carry various medications, medical equipment (e.g. ear thermometer), hand soap (standard stuff causes severe issues), snacks and my own water with me at all times, and an option to carry stuff since my hands are occupied with the hiking poles, so I have a small EDC backpack that's always with me like a purse and can be spotted traversing the sidewalks with poles in full use, a reusable shopping bag hanging from one or both arms, backpack, gas mask, and in summertime I've often got sunglasses stacked on top of that.
I'm not comfortable with it either, but life gave me no choice so....I go for it anyway. Yeah it can suck to be so recognizable. It can also be a positive thing if you're super nice to everyone and earn a positive reputation. I helped out a woman with a flat tire once and she raved about it to everyone around. I'm sure some people don't respect me due to my appearance, and honestly, it's their loss. I'm a pretty community oriented type of person and I simply choose to surround myself with those who can see past the mask and ignore those who can't.
I think this is the crux of the reason many here feel "100%" stealth is either unachievable or unlivable. It isn't because it cannot be done in theory, but rather because in practice all it takes is one little thing--out of hundreds if not thousands of decisions we make about our vandwelling setup--one thing to compromise the 100% stealth, and then once that is gone a fair bit of the other stuff seems a bit silly to maintain.
Best of luck to you!