If it's on a rotisserie and your going to shoot it all at once I'd say close to 3/4 gal RTS. If your stripping in sections just mix what you need for that day (give it the 30 min activation time first). I usually mix up a batch and let it activate for about 48 hours before I start using it. It gets silky smooth.
In case you missed it they now recommend 3 coats to make it bulletproof (so to speak) and you don't have to do the them all on the same day. one coat a day is no problem and even preferred if they are heavy coats.
And I have to say I'd be real inclined to roll and brush it on. It lays out nice and flat and there is something about brushing paint into the pores of a frame that that rests well with me.

But if your shooting I'd do 2 coats give it a day or two to cure then cut it with 180 and get rid of any peel and drips then I'd reduce the last coat about 25% to get that nice sheen and smooth finish. A few days in the sun to cure and your good to go.
Same thing if you brush or roll.

Give me ambiguity
or give me something else