Thanks for the tip about the pH shift with ascorbic acid developers. I kind of guessed that the pH would drift lower. I guess I'll have to monitor the activity and be prepared to adjust things as I go. The potential for bromide build-up is why I plan to limit the films to no more than 10, assuming I can get the replenishment rate settled.
Your statement about the capacity being at least 160 square inches per 500 ml of PC-TEA is interesting. I usually develop 3 rolls of 220 film in a dip & dunk acrylic cylinder using 3 liters of PC-TEA, one-shot. Works beautifully, but I've never been sure how much capacity has been used by those 480 square inches of film. I'll still use it one-shot for 220 film, but it's interesting to contemplate how awesome that tiny splash of PC-TEA is as a developer.
The idea of putting an 8 inch wide film into a tube designed for 16 inches makes me nervous (not enough "hoop" stiffness to hold it in place?). To make me even more nervous... every time I try rotary tube processing, I get streaking, regardless of how I dance, wiggle, and slosh the tube to eliminate eddy currents. I gave up on tubes years ago.
I've been developing large format film by inspection for 20+ years, my "keepers to loosers ratio" is much better than if I use the time/temperature system. (Mis-judge a meter reading, forget a filter factor, close down the aperture inaccurately 'cause you can't see it when it's 2' overhead, and it's easy to get an exposure that's not quite right). By inspection, I can compensate for those kinds of "hiccups".