I've done it a few times in September, and will be putting-on Sept. 12th this year. We always fly in to Indian Creek. Our flows have been 1.5 - 1.8 ft. give or take. The river requires pretty much constant attention at these flows to keep from getting stuck. The best advice is to run your tubes soft. I thought it was nuts at first, but it really helps. You "slime" your way over the rocks. Most folks who go from Boundary Creek seem to go very light. Backpacker style with the minimum required items (groover, firepan, etc.) until they reach Indian Creek. They arrange to have the rest of their gear flown in at that point.
Good luck & have fun.