I'm trying to decide on a tyre for the back of the reverse-trike. Are there any 'givens' when it's for a light-weight vehicle (sub 300kg)?

Low / Medium / High Sidewall???
Soft / Medium / Hard Compound???

Cheers

Soft with a high sidewall. IMO.

I intend to replace the rear hub and wheel so I can use a car tyre and after asking everybody I know with a bit of knowledge and some in the States, who have designed/built reverse trikes, I have settled on 205/50.

A few even recommend getting the tread shaved to 8-9 mm. to make the tyre stiffer in cornering.

Sorry - should have been clearer. It's a car tyre I'm asking about.

Yep, 205/50