Random thoughts....
- Many military jet and turboprop trainers have vertically-staggered tandem seating, in other words, the rear seat is substantially higher than the front seat so that both instructor and pilot have a good view forward including for things like gun sights.
- Some people don't like tandem seating because of poor visibility for the person in the rear seat, which for some light aircraft that require solo from the rear may well be the pilot not the passenger.
- Sooooo...why not have a very light aircraft that solos from the rear seat but raise that rear seat at least a foot (30 cm) higher than the front one for visibility?