last minute tips on using tubulars?

I've had a set of old HED Stinger 60s that I've only used for Olys, mainly out of fear that something happens in one of my bigger (more important) races, I'd just be out of luck.  I have rented Zipp 808s for my Ironmans that were clinchers.  This week I"m doing Vineman and decided it was just too expensive to rent wheels (heck my bike's airfare alone is $175) and I want to use my wheels. I rode them yesterday and LOVED them. Oh my gosh, so so so much smoother than my regular wheels!

Here's what I know:  I have pit stop and I have an old tube to use as a spare. The choice will be to take either, not both.  I have WATCHED my tires being taken off and glued, but have not done it. I know I need a razor, pull it off, and supposedly the rim and the old tire have enough glue on them to hold it on the rim, so all I have to do is put it on or inflate.  The other option is if I get a flat, to use the pit stop.  Either way I will be praying it works. 

Do you have any advice for me?  Or if I'm misinformed, what do I need to do?  Thank you!