The front window on the Scamp
13 & 16 are hard to deal with (altho I haven't heard of either leaking before) because they are a compound curve. You could just cut a hole thru the existing plexiglass and install a flat window with a bunch of shims, but it had better fit under the gravel shield or you will have problems (and you will still have the orig window and its seal). You might try going to an auto-glass place and have them remove the existing window, dress up the fiberglass and re-install it; I beleive it should fit without sealant, just like auto windshields used to before they started glueing them in. The front window on my 91S13 has never leaked, altho I did have to insulate it outside (glued foam to gravel cover) to prevent condensation in cold weather.
The rear window is another story, as its mounting surface is flat. The Hehr sliding windows
used by Scamp, Casita
and a large portion of the entire RV industry are prone to leakage if you don't keep the weep or drain channels clear of road dust that muds up and blocks them.
You can order all sorts of windows from Scamp and others, but they become expensive because of the crating charge for shipping.
Since you are in the Tampa Bay area, you might try Tom's RV Salvage in Brandon (not far from the intersection of the Interstate and Brandon's main drag); they not only have used and dealer closeout stuf of all sorts, but they will give you a good price on ordering stuf from their array of supplier's catalogs.
Pete and Rats
PS I prefer the awning
windows to sliders as you can keep them open in the rain and they expose almost 100% of the opening to air as opposed to less than 50% for the sliders, and they don't have channels to clog. Also, condensation clears from them much faster when they are opened as compared to the sliders.