Sand berms...

I don't know if this will help you... But from reading what you wrote, I'd set my corner speed before i enter the turn, maybe a little slower than usual... Keeping the bike on the pipe, in the meat of it's power... I'm more solid in the sand turns if I can speed up a little through out the entire turn; staying on the gas the whole time...

The problem is most likely that you arent carrying enough speed. The great thing about deep sand turns is that you can usually stay on the power longer entering and get on it earlier exiting, because of the additional traction and loam to assist in powering out and the deep loan helps slow you down as you enter. Practice this turn by itself several times in a row. Practice your entry and exit and then stop and do it again and again. Each time you should try to do it faster. Since you wont be doing laps and arent in a race, you can completely blow the turn by overshooting it or whatever and its no big deal, but this will allow you to figure out just how hard you can come into it to avoid bogging and will help you find the point to get back on the gas after braking. As you improve you will find that you can continue to go faster and get back on the gas sooner.