Hi, I built the interior of my 6x12 cargo trailer, but I didn't want to tackle the 22x30 emergency window instahl, so I hired a mobile rv repair guy to do it. ( Good thing because even he had smoke coming out of his ears a few times with what turned out to be a 6hr. job...& I was right in there helping him with it!) <BR><BR>I left the steel studs/beams exposed on the inside of the trailer where I wanted the window & the night B4 the instahl I cut the interior plywood to the exact dimentions to finish the wall. ( I told rv guy that I wanted his help cutting the window opening in the plywood & fitting it in place.) So I had the plywood, pink fiberglass insulation, & my tools all ready to go. As soon as he slid the window in, I stuffed in the insulation & then helped him cut out & insahl the finished plywood & the window frame.<BR><BR>(I think I shouldv'e paid myself an assistance's fee,..don't you!??)<BR><BR>The beams were 15' apart, so he had to cut the middle one out & then he welded two steel "L" peices horizonally in to make the all metal frame that supports the wimdow. He had to "Jerry Rig" a couple things to make it all work. Ex: The cheap trailer beams/studs are "Z" shaped & only stand out an inch & the window & "L" beams are 2 inches! So, ya there was some head scratching going on, but overall it looks good.<BR><BR>My advice, even if you have some building experience, try to find someone who has some experience with rv window intahlations! It's a two person job anyway.