Here is one type of window glazing:
http://www.trekwood.com/products/969...ber-Seal-White
It may not be the same as yours, but it's a start at what you're looking for. You need to pull part of the window apart to find out which "shape" your glazing is and then find one that will match. If the window doesn't leak and you're just concerned about that 3/8" gap at the bottom. You might find it's a lot easier to clean the gap well with alcohol, dab some silicone into the space, smooth it out and let it cure. You're looking for a very frustrating task to remove all the glazing, clean the frame and reinsert new glazing without risking breaking the window. If that should happen, you're looking at replacement glass and you'll probably never find a matching tint for a 2002 trailer.
This is one time when "if it ain't broke, don't fix it" rings loudly, at least for me......