Acclimation to the altitude is very important.
I cannot stress the importance of drinking water even if you aren't thirsty. This is even more important when you ride.
If you can see a doctor or NP before you visit ask/beg to get a prescription for acetazolamide for everyone in your party.
Studies have shown that prophylactic administration of acetazolamide at a dose of 250mg every eight to twelve hours before and during rapid ascent to altitude results in fewer and/or less severe symptoms (such as headache, nausea, shortness of breath, dizziness, drowsiness, and fatigue) of acute mountain sickness
Another tip that people swear by is taking a couple of Tums antacids several times a day. Be careful as the calcium in the Tums can cause constipation.
Popping an occasional 200-400 mg of Ibuprofen can also stave off the headaches associated with rapid climb and lack of altitude acclimation.
Save the LEGAL recreational marijuana until after you are done riding if you feel that is something you have to try. Avoid edible pot products as it is too easy to overdose with them and ruin your stay. If you must partake, smoke it.
Be safe and try to keep eyes on your riding buddies. If your riding buddy gets into an sled accident, don't rush to get to him/her. You will be of no help if you hurt yourself trying to get to a help a buddy who might have gotten hurt. Snow depth is good but there are still hidden rocks and stumps that can jump you and getcha when you least expect it.
PLEASE MAKE SURE YOU DON'T LEAVE ANY VALUABLES IN YOUR VEHICLE! My car got broken into while I was at the gym and my wallet, credit cards, cash, expensive watch, and other valuables were stolen. This happened 2 nights ago and has been a nightmare with the credit card fraud, loss of driver's license, and identity fraud that has already occurred.