I usually ride on a small river too, and agree with you completely. They don't turn well for d-drives. I think they should have had another keel under there, and I don't think the stepped-back transom helps either because it leaves the boat ass-heavy (dangit Bitzco, leave this one alone...

), and makes it want to carve the turn rather than slide.
HOWEVER, in a tight river, with no other options, is the ONLY time you should ever do a high-speed turn. Unless you want every other boater on the water to curse you.
For the non-river riders:
When the skier/boarder falls, pull the throttle back to neutral. Don't turn the wheel yet. Once the rollers go away (about 4-5 seconds after you pull the throttle to neutral), turn the wheel, idle through the turn, and get back to your skier. The reason? It minimizes cross-rollers and keeps the water calmer, longer.