The comment from Stan909 used to be the case, but it isn't any more. When you have the conversion done by Ursa Minor vehicles vehicles, they put an access hatch in if you don't have the sunroof. This is what was done with ours.
Hopefully our converted Element will last for many years, but I'm looking at the Ford Transit Connect for 2014, taking most of the rear seats out, and putting one of these on it.
At present I camp in what I call a B-minus: a Honda Element with a rooftop conversion providing an upstairs sleeping area, done by Ursa Minor in San Diego.
Elli now is coming up on 100,000 miles, and I've begun to think about a replacement. I would prefer it if I had something a bit larger, but not as large as a GMC-, Ford-, or Sprinter-based B.
Here is what I want:
1. A vehicle that is easily driven every day. I know that many of you use a B for everyday driving, but I don't want anything that large.
2. A vehicle I can finish myself. Class Bs come with all kinds of things I don't want: hybrid fridges, elaborate cooking facilities. I use an Engel ice-chest, a little Coleman propane stove, and a Wally-World microwave under the home-constructed platform in Elli. In other words, I don't mind improvising to some extent.
3. A vehicle that is a little bigger than Elli. She can be a little small, particularly if I'm stuck indoors because of weather. And I carry enough "stuff" that I normally take Rover, a little motorcycle trailer that holds about 20 cu. ft., when I go camping.
4. A vehicle that can take a bit of dirt. Elli has rubber floors. One reason I won't consider larger SUVs is that they come with carpets, plush seats, and other luxuries I don't need and don't want to pay for, which will rapidly degrade if they are used for camping.
5. A new vehicle, not an old one. I've considered the old style Suburban, for example, but I don't want associate maintenance problems.
6. A reasonably economical vehicle. If a Sprinter can get over 20 mpg, then I want the vehicle I purchase to do as well as or better than that.
OK, so far so good. But here's the basic problem: What vehicles are available which meet my conditions and are of the size I'm talking about: that is, between the Honda Element and (say) a Roadtrek 170?
There seem to be several such vehicles in Europe and Asia, but not here.
I hoped the new Nissan vans would be suitable, but they're just as big as regular Class Bs. The smaller Ford Transit van is about the size of the Element. Larger SUVs are not "stripped" enough.
What says the group?
One of the reasons that I enjoy my B- Honda Element conversion is that I like to be outdoors. Staying inside Elli is something I do only if it's wet or cold.
Something I've noticed on every campsite I've ever stayed at is this: The smaller the rig, the more the owners are outside: sitting under the awning, cooking, or walking or cycling. The bigger the rig, the more the owners are inside, even if it's nice weather. I offer this as a general observation: it's obviously not true for everyone.
So I'd suggest you ask yourself this question: Am I considering this life because I want to be outside as much as I can, using my RV to retire to for sleeping, for evenings, perhaps for food prep. and storage, or for bad weather? Or do I intend to treat it as a substitute home on the road, remaining indoors as much, or nearly as much, as I do at home? If it's the latter, I'd counsel getting a big rig.