Ok, then how about making it a fatty for a start? I propose this 16“ steel rim - it‘s even made for a uni! https://www.vlechtservice.nl/en/p/velg-bromfiets-16/. Not 100% sure if 44.5mm is wide enough, though.
Edit: maybe this should be moved to the Micro Machines: Tiny crank and tiny wheel Megathread …