Need to replace my windows. Tips anyone?

[wired]

I am needing to replace the homemade windows in my TD. So far I have been unable to find a manufactured one that is the same size, and the ones I do like are a bit bigger than the existing ones. Can anyone offer any tips on how to enlarge the window opening without mangling the aluminum outer skin and/or shredding the interior plywood? I would probably need to enlarge the opening by 2" in width and by 1" in height. Existing window cutout is 14X22
I am liking Grant Whipp's from Lil Bear Tag Alongs rectangular crank out screened windows. He makes a 15X24 or a 12X18. (http://lilbear.teardrops.net/parts4.html#windows)
With a smaller window I am not sure how to go about adding filler material and am afraid I would have to use large trim pieces to cover the filler pieces, which I would prefer not to do.
Does anyone have any suggestions? Or perhaps someone can direct me to a good source for manufactured windows.
Thanks!
Paul

[CarlLaFong]

I would make a plywood or MDF template of the new window cutout and use a router and a top bearing bit to cut it larger. Use double stick tape or screws to hold the template to the body. If you use screws, be sure they're under where the new frame goes.

[doug hodder]

What he said....and I'd punch some small drill holes in the 4 corners so that you know where they are, then tape off the interior with some masking tape to minimize tear out with the router. Depending on wall thickness, it may take 2 passes to cut the new opening with a router, if going larger. Doug

[wired]

Thanks for the tips, gentlemen! It sounds like a good approach. Now I just need to figure out what windows to purchase...

[aggie79]

I concur with everyone above. You may want to tape a cardboard box to the interior and cut a hole in the cardboard box for a shop vac hose. This would help control the aluminum "sawdust".

Take care,
Tom