You can use sites like RVTrader to do the searching. Put "Rear Living, Mid-Bunk area" into the key words and that should help some. The only issue is it will show you every single RV that meets those criteria, not just the type or class, likely giving you hundreds of "hits."
Rvingplanet.com lets you select the types of things you want (like an Amazonsearch). It will give you a listing of the brands, which meet your criteria.
There may be others out there, but most I've seen tend to push the consumer to a particular brand or something they have on their lot.
When we first started out, we bought something we thought was going to meet our needs. We then had a year of researching to find our next one. And so forth. With each new RV, we have looked around at more and more options, refined our "Must Haves" and "Won't Tolerates," and we finally believe we have our perfect RV. We'll see how long that lasts.
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Ben and Doreen
Home Away From Home - 2017 PT Crusader 315RST
TV - 2016 Ram 3500 Laramie 4X4 6.7 Cummins Diesel
Never Enough Time Camping!!