Not necessarily with the window part, but try reading "The Traveller by John Twelve Hawks" It's a series of 3 books. Mind you that book is like 15-20 years old, but it's about a guy living off grid for pretty much that reason.

The confidence gap by Russ Harris. To give strategies to overcome the nasty voice in my head that will likely emerge criticizing everything I did/do, coz ya know I'll be time travelling and likely put my foot in and generally do stupid stuff that doesn't belong in that time. So the inner meanie might wanna come out and "beat me up". Better be prepared on how to overcome that meanie when I need it.

Try asking on r/leathercraft. There are people who take commissions. A well made bag will last you for life.