First suggestion would be to go to a dealer that carries a line of TCs. Look at what they have to offer and decide how big/small you can go. Realize you aren't looking new, but a collection of new units will make it easier to compare.
A long bed Crew Cab with TC isn't a problem if you are only talking an 8 or 9.5 footer. Can park it in any parking space without much issue. I don't think you are a candidate for DRW if you are staying small. The ease of parking the SRW with/without the TC is one of the reasons my wife loves the TC style.
The extra seat is great for carrying gear and really only a few inches longer than a extended cab. However, the extended cab would be much easier to find in the years as they were much popular.
Second, it is hard to go wrong with either the Ford V10 or a bit older and Ford 460. I have been looking for a 92 series F350 Crew Cab long bed w/460 to restore as I had one to tow a 30' TT and it did fantastic so think a TC would do even better. Even a Chevrolet 8.1 would be a good candidate. Only issue would be to be leery of the 96/97 V10 as I hear they had spark plug thread issues in the block (though research to confirm).
Think if you look around you should be able to find a 2002-2005 Lance 815/835/915 in your price range. Well built camper, can be easily repaired if necessary, and light weight. Easily carried by above trucks where you will be traveling. You do want to stay away from a basement model as it raises the center of gravity (COG) and makes off-camper situations trickier.
May also want to look at a new palomino pop up. Quality isn't that great, but the price is low for a unit if you are basically looking for sleeping quarters. Used units also hold their value well if you keep up on the maintenance preventing lot.