Flippac Rain Fly

We are going to get a rain fly for our Flippac and wanted to get insights/thoughts from Flippac owners. If we don't get a used one and purchase it new from Slo Sail we wanted to hear thoughts/comments on having windows added and, or extra straps and triglides.
I bought a new fly from SLO several years ago. Vents N/S and one window/one vent E/W on each side. Works well. Typically, I don't find that a lot of ventilation is needed when the fly is on. I think just two N/S would be plenty, and windows on all four openings E/W would be desirable.

I use a combination of bungees and straps.

The biggest issue for me with the SLO fly was needing to seal the seems. It was challenging to lay everything out so the seams were flat and get it sealed properly. I used SeamGrip and did two coats on the inside only. Never had a leak.
My biggest gripe is the cost and the fact that they don't do at least round-ish windows... charge a lot for simple square (undersized?) windows, and as mentioned for that price you have to seal your own seams.

I would almost see about a custom built one next time around...