I was just reading a thread on another forum about how people transition to small, light RV's to big ones. Typical was "We're using a popup trailer now, but when the kids are gone we'll retire and get a Class A"
My response was- I had a Class A. Now I have a Chalet. When the kids are gone I'll get something different but not bigger.
Then I got to thinking about the advantages of a popup- it tows small but camps big. Unfortunately the setup and cold weather performance rules them out to me.
But I got to thinking- What about a Hybrid. No, not one of those big hybrids. But thinking about building a teardrop-ish thing with a conventional popup trailer as the doner. Use a 10' box popup. Leave one of the front bed slide in place and construct the trailer such that it's usable closed up. If weather is nice and it's more than a quick overnighter, a hatch would open in the front and allow the bed to slide out, freeing up more interior space.
My thought is somehow do a bathroom with porta-potti & sit shower in the area between the wheel wells just ahead of the kitchen bulkhead. Or (more likely) crosswise bunks for the kids there.
It's just my first thought on the matter.