if you fit upright woods at either side of the window you can then fasten the window either side to the new woods and also any internal covering that you want also choose the wood size to match with your insulation as well
That's certainly something I'm thinking of doing, but I might just squirt a load more of the pu adhesive into the gap between the frame and the aperture. Once set, it's as good as a mechanical fixing I think. Then I can use insulated plasterboard direct as insulation and finish in one, no wood. Bolt through the bash panels to the outside to fix. Simple.
The Hi-Lift is a very useful tool. Ive straightened fence posts and pulled out small trees and bushes with mine. Only once was it used to jack up my Land Rover