In the "Monk & Robot" novel series by Becky Chambers, the human protagonist drives an electric bike towing a small caravan which seems quite spacious from the descriptions. Existing bicycle campers are generally low and narrow to limit drag, leading to cramped conditions and storage only accessible from outside.
While brainstorming, I found the Slidavan telescopic caravan and decided to expand the concept to three segments to have standing room and a loft bed. The raising mechanism should be similar to the one shown in this short animation.