Excel provided the solution (it's disturbing how often that good ol' computer program is the answer to my problems!).
I simply scheduled time for Matt and me to be together, alone, focused on each other and the weight of the moment.
The wedding day will be packed, in a relaxed sort of way. We'll start the day among friends and family over a leisurely breakfast from 8-10am. Then we're off to the ceremony site to set up and rehearse. Next we head to a family luncheon (hosted by Matt's family) for a quick bite. Then it's back to Sunshine Mountain to help with the last hour of a two-hour food prep session for the reception. After that's finished, Matt and I hike to the top of the Sunshine Mountain Inn property to spend 45 minutes of quality time together. Finally, it's back down the mountain to get ready for the wedding (luckily, I'm pretty low-maintenance, so that won't take much time).
Phew! It's funny how schedules simultaneously make me feel less-stressed and more-stressed.