Lots of advice, lots to recommend, but what exactly is it that you want it to do??? That would sure help.
And after having camped in everything from a tiny pop-up to a large 5th wheel, one thing can be said; if you really want to take something with you bad enough, you'll figure out where to put it and/or make room for it somehow. You wouldn't believe how much crap my wife had stuffed in the little pop-up!
And for what it's worth, weight probably isn't really as much of a concern as size is unless your tow vehicle is undersized for the trailer, in which case you have bigger issues.
Think outside the box; literally! If you're in your camper or outside, your tow vehicle makes a good storage closet; likewise, when on the road, you're not in the camper, put it there. Then like the Boar's Head commercials state: compromise elsewhere.