If you're rowing a raft (not a cataraft) with a frame, but no/minimal gear or passengers - especially in higher water or where you are hitting bigger waves and holes - then you are in flipping city. You need weight. You used to guide on the Grand so you have probably seen guides bailing water INTO their bucket boats at high water for extra momentum when hitting the big stuff. Sample principal - and if you have a bucket boat, well start adding water. Otherwise bring some friends, even put paddles in their hands, and if they're attractive - even better. Worst case they can hand you beers while keeping the boat from flipping. Otherwise consider carrying water jugs that fit securely in your frame - you can fill them at the river - four full 6 gallon jugs weight 175 lbs or so. That's not a lot of weight, but it will make a difference. You may also decide to run more conservative lines - or embrace flip recovery.
Second option, get a cataraft. With vastly less surface area and way better hole punching ability they are much better suited to a lone rower with minimal gear. And they're faster and more maneuverable.