I bought a Sunsport last year for the reasons you list. Been very happy with the size and configuration of the boat.
I'm not sure about either of the ones you listed. I don't see any info on the iboats listing. The boattrader boat looks rough and also no real info.
The big question on these boat is the stringers. I assumed they needed to be replaced if they hadn't been already, or if the boat had an exemplary, 1 owner, low hour, stored inside history.
I'd be looking for something from a private owner that can give you the history of the boat.
1986 Sunsport Skier with Acme 543