On the 4.8 I use a short shaft 6hp 4 stroke which is mounted directly to the transom. I have a space advantage on my transom as there is no 'A' frame.
Peter (Ribald) had a 4.8 with an 'A' frame, which I believe did not allow for direct mounting of an aux outboard.
On the 5.8 we had an outboard bracket which proved to be unreliable, so we now mount a 5HP (long shaft) 4 stroke directly to the transom. We find it much quicker and easier to use the engine this way, and more importantly it has proved to be a robust mounting method.