What size drying tent?

I wouldn't dry in a tent. It's too small of an area, and you have to control the environment of the outer room anyway if it's going to exchange air with it, otherwise the effort to do so in the tent will fail. Any circulation will be too strong, imo. Shouldn't have a breeze going across the buds, it'll just dry it too fast. You want circulation in the room, but it shouldn't impact dry times... merely enough to keep RH consistent rather than heavy in one area. That takes very little wind to accomplish in a small room. I use an old tent frame in a small, cool room with a 60% RH. I wet trim and snip down to bud-sized bits and still get a 10-13 day drying time. Leaving them on the branches, dry-trimming or even hanging entire plants are tools to impact length of drying times. A 36" rack can hold over 1/2 lb in a single layer and well-spaced buds. Believe a 24" rack is just under 1/2 the area, so 1/2 the capacity - 1/4 lb per tier is a safe/conservative estimate. So, a minimum of 4 tiers of a 24" rack, but you should go larger, because it's a very cheap initial cost and last forever if you clean and don't treat them roughly. Maybe you want 1 plant per tier regardless of filling it up. Makes keeping plants separated easy too. If you use HEPA13 air filters in the room, you can even go with the cheapest racks possible that don't have a full mesh covering, not that it can keep out finer dust anyway... an air filter in that room is still wise with the zipper accessed racks.