I'm about to take on my first infusion project, have been using prepreg and regular vacuum bagging to this point but this part is too big to fit in my oven. I'm confused as to how the resin flows from the spiral tubing into the reinforcement if the tubing is supposed to sit on top of the peel ply as all the tutorials say?

Yeh use something else, Strechlon is horrible for infusion. It's actually a waste anyway, as anywhere that the bag has stretched into position will actually relax again once the resin flows in and you lose full consolidation. These areas will then be large areas of bridging that will fill with resin.