Try the boaty section below but think you have answered your own question to be honest.
Stern is deeper than a rib/sib

 

Thanks - ill check it out. Yeah that makes sense. Its an expensive game 🫣😁

 

I would have thought a 6hp short shaft would be fine, especially if you fit it to an aux bracket. Personally Ive never had an aux outboard or felt the need for one.

 

Only if the engine runs underwater!.
Unless you Stowe engine then place on stern when needed!. "Risky"
your Aux sits on a flip up/down bracket so when dropped down in use the prop is clear of hull/wash and in clear water to provide propulsion and a short engine won't clear the freeboard on the stern esp as the backwash will drown it.

 

Thanks. I think ill give it a go to see if it gets me by for now👍

 

Cheers guys for the responses.All good info to consider.The boat has that exact bracket so I think ill use it for the time being until such times I can get a long shaft. 👍👍