I just needed to adapt my plan. My original intent was to practice shooting on the move. Instead, I found a small "island" of relatively dry ground, at about the 15 yard line. I decided to work on drawing and getting on target quickly. Setting the new shot timer set to a random start, gave me something to react to. Accuracy seems to degrade when reacting to the buzzer over simply drawing at will. I stood in that relatively dry spot followed up each shot from the holster with one or two more shots on target. Using a paper USPSA practice target I alternated between more rapid center of mass shots, and slower "head" shots. I don't know exactly how many repetitions I did, but I fired 240 rounds this session. And the time went very quickly.
The down side of the day was that I forgot to bring my boots. Getting to and from the berm to refresh the target paper required some careful negotiation of the slippery ground, all the while trying to keep my feet relatively clean. However, on the bright side, all my used brass was left in a nice compact pile for quick pickup at the end of the day. My shoulder may have been a little sore from the repeated drawing action, but my back was saved from a lot of bending over.
Any day of shooting beats a day of, well, just about anything else. Regardless of the conditions!