[Christ]

Yeah, you need something to calculate a basic load map. Most small engines don't need timing advance, etc... so no need for all that jazz, but you at least need a pre and post reading to keep response times, and to have a little bit of protection in case one or the other fails.

TPS and O2 might cut it together, with not much else. In the fuel mapping, assume a constant VE (Small rev range, calculate it yourself.), determine the proper fuel/air ratio for the intake volume, and set it up so the TPS alters the fuel map, and the O2 is used as a secondary reference.

You could probably befriend a tuner geek that can write a simple fuel management system for you.