YES YES YES YES YES!!!!!!!!!!
abaya has it right - you should just wear an emergency pad/liner and you won't have to take it out until you're done climbing. I only say that because it's your heavy day AND you're going to be doing a lot of wiggling... that's the only recipe for leaks I can think of. But absent any small leaks, it's definitely the way to go if you want to avoid running off to the bushes during the adventure. Anyway, my friend just started using hers and she had no problem with the insertion after I gave her tips. She said it just popped right in. So I will give you the same tips.
1) Know the direction of your vagina so that you don't shove the cup into any walls. Stick your fingers in there first if you need to make sure you know your vagina as well as you think you do.
2) Don't try to do it too slowly because if it pops open on the way in (which it will if you do it slowly), it will hurt. So just fold it up and shove it on in. You can always adjust its positioning afterward if you really need to. The little removal tab is good for such a job.
3) When you take it out, don't pull it straight down. Wiggle it side to side as it comes down. That will reduce any discomfort you might experience from that honking rim part coming out.
Happy climbing and Divacuping!