It sounds like you should be fine with some fiddling.
It would be best if you were able to try everything at home, with all of the rest of your gear at hand and a warm bed to bail to if needs be on Thursday night. It would be better if it were car camping, where you could get more stuff out of the car to help or bail to the warmth of the heater in the car if needs be.
However, if neither of those are possibilities, then I would also bring a small section of CCF pad from WallyWorld (they sell them in the $5 to $8 range) to place underneath the partially-inflated pad you already have. The advice given before me here is also very good: keep drafts around your neck to a minimum, wear a warm (wool or synthetic, not cotton) set of clothing and a good hat, and be ready to make changes if you feel cold. Don't wear wet clothing to bed.
Are you going to be camping alone? If not, there's another failsafe in place, just in case things go sideways.
Otherwise, have fun! Let us know how it goes!