Hi Kathryn
I have a Dodge Caravan with stow and go and had a friend take the seats out for me. You should be able to travel comfortably, have good stealth, and get pretty good mpg. Hopefully your back windows are tinted- if not I would recommend it.
I live on a very tight budget but manage to get by. I spend 70 a month on my phone, which has unlimited data and that is also something I highly recommend. I pay 90 for insurance with roadside assistance- I know that's high and I have a spotless driving record too- but my credit score is no good so that's the cheapest I can find. I have a 20 a month gym membership, a 10 a month Netflix account, and a 10 a month Kindle Unlimited subscription. Those are my only bills.
The rest goes to gas and food. I find I am even able to save a couple hundred each month for emergencies, although I already have an emergency fund that I try never to go into. It's enough to replace my vehicle, and that is probably the minimum amount you should set aside.
Unlike many on here my van has really not been converted to live in. I keep my camping equipment in stackable tubs I bought from Lowes, and those fit on one side and I sleep on the other.
When I boondock at parking lots I put up my sunshade in the window and have a small tarp I shove into the back window. It is obvious I am sleeping there, with the sunshade and all, but I actually prefer that. I feel someone is less likely to mess with a vehicle that looks occupied than one that is empty. I could be wrong- but that's my theory. And I only park where I am allowed. Walmarts, truck stops, typically where others are resting as well.
I don't have refrigeration... And I usually just eat what I need to not be malnourished. Breakfast is a slim fast and a banana. Lunch is a high calorie meal replacement protein bar (MetX I believe they're called). Dinner might be something I buy out, but often times it's crackers and peanut butter with a fruit cup. And an Ensure shake each night. None of that needs refrigeration, and if you have any weight to lose you'll do it on that
I have a portable power bank that I got off Amazon that has about 20,000 mah. It recharges my phone a few times on a full battery. I charge it, and my phone, at various places- usually a public library or a Mc Donald's that has outlets available.
So far this set up has worked for me with one exception... I do wish I had solar panels for a fan. I have a battery operated one but buying 8 d cell batteries once a week is a hit on the budget. It'd also be nice to power my phone without needing public power. It's on my to do list, but having no idea what I need or how to install it is an issue. I'm not near as handy as some on here.
I do spend time at campsites and for now I am questioning if it is worth it. So much of what I carry is for camping, and it is an expense I wonder if I shouldn't cut out. It is rare to find a campsite where I have signal, and I miss my daily trips to the gym. Still, I haven't ruled it out. It can be relaxing to stay put and know where I am parking every night for a short while.
I hope you are able to enjoy traveling. There are many apps for your phone that are handy- All Stays has free ones that show you where every major truck stop is, every rest area, even every Walmart. If you have any questions just ask on here- this site is great- or pm me and I will send you my number. Good luck!