Which Red Air did you get? We're huge fans of the brand, construction and toughness wise they're head and shoulders above all the others. We have been using them in our school for two years now and they're still like new. The 10' and 10'6 are probably the best for river work. Don't be afraid to put serious amounts of pressure in them. Their multilayer skin construction can take it - we keep our school boards at 25psi+, so they're incredibly rigid. (
Don't try that with any single-skin inflatables though!).
Here in New Zealand, the NZ SUP Champ Lynden Kennings is using Red Airs for his river riding, and he's absolutely firing on them - tail-sliding them off rocks, taking huge drops, you name it. So - depending on which Red Air model you got (the 11 is a bit too flat-rockered for serious river riding, while the 9'4 is too thin in the nose), you've got all you need right there for some high performance sport.
Billy D
Northland Paddleboarding