I have bought directly from Garhauer, as well as various dealers. If the firm carries one model, they can get the other model--there are both the long and short arm, but also the different size of tubing and weight rating.
I would agree, that you are best off with the lighter boat. We put a 60# boat on the cabin top, with little problem. I just made an aluminum spreader bar, which will make it even easier. The 2.5 Suzuki is an outstanding motor--and I think closer to 3/ 3.5 hp (comparison with a 3.5 hp 2 stroke Merc). It is only 30#.
I use the Torqeedo 1003, and find it to be a great dinghy motor, and far lighter than nay outboard. (Dinghy is a 9 1/2" air floor West Marine boat).