I looked into doing as you describe but ran into a problem. The power awning mounts very different than the old one. The new arms are secured at their top edge by two large lag bolts that must go into some solid wood - not just luan paneling. The location for these is just under the gutter. Unless your RV has some blocking for this or wood framing in that location, there's nothing to secure these bolts to.
In our case we have a thin aluminum channel up there that the side wall slips into. We had nothing solid to mount to. The existing blocking was directly behind the gutter, not under it as the power awning required.
I suspect some shops just screw into the thin paneling and use lots of caulk to secure the awning arms to the side of the trailer but the instructions plainly spell out what the structural requirements are.
