River Boat plans

Hi I moved to the border of Costa Rica and Nicaragua on a river called the Rio San Juan.  I need to build a small skiff type boat that would use a 10 to 25 hp outboard motor to fish and get up and down the river, something light because gas is expensive.  Lots of good hardwood here, planks mostly.  Thinking of building a kayak also.  Would appreciate any suggestions.  Thanks Darren