8x10 is almost a palace for one, decent for two, and at least with sil-nylon, still light and compact. It takes a lot of room and a lot of lines and stakes to pitch well--definitely more fiddly than a simple tent or tarp shelter, so consider set-up time in the equation.

Almost think I'd prefer 9x9. For one, being square simplifies pitching in a diamond pattern compared to a rectangle.

While flat tarps are the most versatile, I prefer shaped tarps with catenary center line. Stronger and pitch tauter, so flap less.

Cheers,