A couple of tricks for suffering through bad mounds.
1) swipe out all the loose material with your foot to help stabilize your landing. You may have to keep doing this throughout the game if the mound is not made of clay.
2) step about 2 inches forward of the pitching plate when you plant your posting leg. Works good with one umpire games from stretch or wind up or two umpire games from the stretch because the umps can't tell you are not in contact with the rubber and it allows you to miss the big ditch in front of the pitching rubber and allows you to land beyond the foot strike ditch of the other pitcher.
3) kick the crap out of the leading edge of the front foxhole and use the material to build up/fill in the hole on the leading edge of the rubber.
One thing I used to do for my son when he was scheduled to pitch on a crap mound was physically go to the ball field the day before the game or several hours before the game with a lawn and garden pump sprayer full of water, my rake, and my tamping tool and reconstruct the mound. If it sits overnight and is allowed to firm up, it can last most of the game before turning back into powder. Check the town schedule to make sure there isn't a game or practice scheduled on your field between your maintenance work and your kid's game.