Greetings & Welcome!
While the promoters like to promote cargo vans because they cost so much to convert, in the real world, non promoters hate them, and regret ever getting suckered into them. Only hard core hermits are happy living in a box without windows. There’s a good reason that you can’t buy factory camper vans without windows… NOBODY WANTS THEM!
There’s really only 2 ways to solve the problem, either add a lot of windows, or cut your losses, sell it, and get a passenger van with opening windows., and a pre-finished interior.
A passenger van will save you money starting immediately, throughout it’s use, and when it comes time to sell it, it will be worth more than a windowless camper, and much easier to sell too. Passenger vans are usually in far better shape both physically and mechanically than cargo vans too, and they also frequently get considerably better gas mileage too.
With a passenger van you can simply remove the rear seats, and your floor, walls, and ceiling are already finished. With windows, a $20 fan will give you better ventilation than $500+ in roof vents, and you don’t need to add holes in your roof which will eventually leak.
Forget what the promoters say, IT’S ALL LIES!!! The moment anybody suggests you need anything expensive, stop listening to them. My total conversion cost under $300, and I have all the conveniences of a $100,000 motorhome except a microwave, which I don’t have because I couldn’t justify the weight or space for what little I’d use it, not because I couldn’t have one. I have unlimited power without the need of solar panels or expensive batteries. Heating, cooling, & ventilation that has kept me comfortable from -60°f to 120°f. I have a very comfortable bed & seating, full kitchen, toilet & shower, etc.etc. I also get 18mpg with my 1973 high top Dodge van that I paid a whopping $700 for 11 years ago, and it has been comfortable & reliable the whole time. I live & work inside my van, so my comfort, and it’s efficiency & reliability are very important to me.
If it was me, I’d ditch the cargo van, and start over with a passenger van. One of the worst mistakes of my life was letting the promoters convince me into converting a cargo van. A mistake I will never make again, and try to help others to avoid before it’s too late.
"Friends don't let friends convert cargo vans." ~ A Friend