BOD,
Our affluent and high tech society tends to overlook some tried and true solutions that have well served needs. 15 years ago there were more outboards than jet units on boats on the Skagit River, and tons of salmon and steelhead were hooked by anglers on such craft. You need to think about where you're driving if you like the lower unit, but the record shows it was commonly done. The average Skagit boat used to be 16 or 18' by 54 or 60" bottom (built from plywood) with 40 to 60 hp outboard. I've had a couple friends with Hewescraft 14' river-runners (it's almost 15' by 48" bottom) sporting 25 hp outboards, and those were serviceable craft. I use to use a 25 hp on a 14' Lund. Admittedly, I haven't seen those kind of boats on the Sky or Snoq or Snohomish (I don't fish there), but I think they would serve, although you wouldn't be able to navigate the upper Sky.
A boat like that also does Puget Sound duty.
This reminds me of an old fisheries creel census story from the late 70s, early 80s on north Puget Sound. Anglers from many, many boats were censused, from the smallest tub that would float a fisherman to near frigates. The highest catches of chinook salmon correlated with usually solo anglers using boats that averaged 15' long and powered by 15 - 25 hp outboards and using mooching gear. These were the guys who did one thing and did it well, far outfishing the rest of the recreational fleet by nearly an order of magnitude. The upshot is that the fish won't ever know how much or how little you spent on your boat.
Sincerely,
Salmo g.