A few more comments to peruse and cherry pick thru that might apply to your situation:
1. An epoxy finishing resin should have a non-1:1 mix ratio, and should be thinner. (They make stuff 1:1 for mixing convenience by adding filler. This is fine for gluing operations but not helpful for cloth layups.) This helps a lot with wet-out on lighter weight cloth. Ez-Lam 30 minute has always worked great for me for a variety of jobs and down into 1/2 oz cloth. Using filled epoxy for laminating causes issues because of the (much) higher viscosity. Guys try to get around this by adding thinners. That is a poor substitute. Sure, I've done it and learned it is (much) more work and doesn't always turn out good. In particular, using isopropyl alcohol is a terrible idea. You are trapping water in the resin. If you combine this with colder air temps you can easily create a situation where it never does completely cure. The advantage of West Systems is that since they developed it for boatyards--in unheated boatsheds--they formulate for lower cure temps.
2. You can avoid stress risers in a wing center by using two layers of cloth, such as 1/2 oz. per sq. yard or 3/4 oz. One patch/reinforcement is larger, the other smaller. The edges should not line up. Pick your druthers about which should go on the outside. You will "float the cloth" if you put the larger one on top and likely have a void at the edge of the underlying cloth if the layup isn't awfully wet, or if you don't press the layup with a peel-ply and foam pad technique. You can put the two layers down at different angles and improve the overall strength. You didn't say if you cut the wing out to do this repair or not, or even if it was a full fuse job or a profile, but depending on what you have to work with, you can adapt the reinforcement. Do not run a glass patch clear across the center section planking LE to TE and then terminate at the edge. That focuses--even more than most construction methods--all of the bending stress there, where if you doink it again it will more easily break.
3. For an in-situ wet layup, especially a repair job where things can be bulky/awkward, just paint on the epoxy resin, drape the cloth and do the TP roll method if that is your preference. It works.
4. For a wet layup where maybe you are reinforcing a wing or a fuse--or anything else, for that matter--but especially as part of a normal build, cut all your layers beforehand and lay them out on a table where they won't get snagged or warped (pulled out of square). If you have good access to the whole part, and aren't trying to fold the glass over a small radius, you can just paint on a shiny coat, and drape the layer on. There are techniques to getting it right where you need it. You don't want to be pulling the glass around or it will lose it's shape. If you are doing a second layer, best to lay that on the bench and wet it out on top of a piece of MonoKote backing plastic. Then drape it and the plastic over the area and squeegie with a credit card. (You can wet out all the layers on the bench, stacked one on top of the other, and then drape just once. If your resin control is not real good, this lets you get the excess out before it ever touches the plane.) Leave the plastic on until it cures. If you are going to press it between upholstery foam blocks you can do that next and get a bit of weight on the stack so the glass stays as close to the wood as possible. The idea here is that if you painted on just the right amount, it will leave a very smooth finish on the outside where it was up against the plastic and you won't have much sanding or filling to do. Even more important, you minimize the pinhole problem if you plan on painting. If you sand into the glass fiber during the prime/fill process, you create places where, despite the Volan treatment of the glass, the paint doesn't want to go. Pinholes create more work in final finishing than the entire process combined--if you get them. Be sure to use plastic backer that does not have wrinkles or you will replicate them in your finish. And, be sure that what you use will peel off the epoxy once cured. You can buy peel-ply from ACP, but the MonoKote backer works well.
5. If you decide you have to put another layer of glass down, or want to fill with epoxy resin, then you need to get the gummy surface film off of the prior coat of epoxy. This is the amine blush that bleeds out during curing. Wiping down with lacquer thinner works.
6. There are a lot of reasons that epoxy is preferred over polyester resin. Right at the top of the list to keep in mind is that the polyester catalyst is really dangerous. Sloppy handling leading to contact with the eyes is said to cause near-instantaneous blindness. It is also easy to end up with a "hot" batch when mixed in small quantities which means that your finished part may be brittle. And so on.
7. Guys always are tempted to use epoxy paint to lay something up. I've never seen that work well. (Two cases where club guys tried it and reported their results.) It isn't glue and it isn't laminating resin.
Hope these comments might be of use somewhere along the line