My experience is that SOTs are generally under-rated for the weight they can carry. If you're under - and well under - the claimed capacity, I have confidence that you'll be OK.
It will be a slow paddling boat. Length = speed, so lack of length = lack of speed. That's not necessarily a bad thing when it comes to fishing. I like low and slow.
- Big D
Pull-Up Strap Handle Kit
Paddler's Truck Rack