Kelly, I have never worked with fibreglass before I bought a Trillium
. I don't claim to be any kind of expert, but I am happy with my work.
A nice thing is that the tools are cheep. The window job needs a screw driver and some cleaning tools. Buy some new stainless steel, pan head, 3/4" screws and some butyl tape. The screws are best purchased at a fastener store, bolt shop. They will have a box of 100 for what Home Depot will charge you for 20. The butyl tape can be purchased at an RV parts department. Get the 1" stuff. The 2" is too wide. Though the extra can be cleaned off.
Unscrew the windows
and throw away the screws. The old butyl tape will hold them in. Pull them out from the bottom. They have a funny shape to them and probably won't come out if you pull them from the top. Clean off the old butyl tape from both the window, and the fibreglass. I put the new butyl tape on the window flange.
Before reinstalling, check the plywood frames that they screw into. If the frame seems dry and solid, they are fine. If the wood is soaking wet, and / or rotten, they should be replaced. This is a time consuming job. You need a sharp putty knife and lots of manual dexterity. Separate the Ensolite from the wood with the putty knife. This process is time consuming and I found it difficult to get the corners of the frame to separate from the Ensolite. I think a gouge chisel would be useful for this. Something like this:
The frames are made of 3/4" plywood. They don't have a 45° cut where they join. The top and bottom pieces are long and beveled on the ends and one side. The side pieces fit between the top and bottom pieces and are beveled on one edge only. The cross section of each piece of frame is 2.5" on the face that is against the fibreglass and the bevel is 45°. Marine plywood makes sense in this application, but I just used regular plywood and painted it with floor paint
The presence of kids will be a distraction, but you can do it. When you run into road blocks, we will be here to help. It would help to have a dry place to work. I have a double wide carport tent that I use for this.