I would suggest the following products vs a plywood platform with holes. You'll end up getting mold from moisture unless you're very diligent with your airing.
I went with mattress insider's "hypervent air-flow" and the cost for a 39" wide x 72" piece twin bed size was $60.
It is 2" short of a standard twin and I could have ordered an 84" piece for $70 but I thought this was close enough.
Researching more and finding the correct google word for this, I could have saved money using "MortairVent Rain Screen" A roll of 40 ft is $109 at HD, enough to do 6(six) twin XL's. I purchased a roll as I have other projects that I can use the remainder for.
The product is almost identical with the exception of the thickness.
The mortairvent is 10mm (3/8").
I thought those of you who meet up could split the purchase of the MortairVent roll, (it cuts with regular scissors) and a twin size would only cost you $20., a queen size $40.
Having both of these products, there is virtually no difference. The Sailrite product (~8mm) is marketed for boats which have much more moisture than a van or RV (lets hope) so I think the 10mm MortairVent will do just fine.
In the photo link you can see the difference in thickness. The two products are adhered to the fabric opposite of each other but the blue stays attachedbetter.
https://vanlivingforum.com/attachments/mattress-ventilation-jpg.29085/
