extremely light weight footprint (or for keeping your meat clean). I doubt you'll find anything lighter. Tyvek is tougher but not lighter or more compact or more water proof than this. More than two 2-man tents worth.
https://www.ebay.com/itm/202865531309
Another thing that I found that works is Bohning Feather Dri for keeping traditional feathers from absorbing too much moisture and weighting them down. And it's a lot cheaper per unit of volume than the others, https://www.3riversarchery.com/feather-dri-water-repellent-powder.html
I'm also an engineer and like SW, but as ewescue said above, it is very expensive. And, if you've never used a CAD program, it will take considerable time to become proficient. But, I've heard good things about Chief Architect, which is much more affordable. There are YouTube videos available...
I can't imagine someone not letting you recover an animal that was shot legally on property adjacent to theirs. But, then again, I can't imagine the actions of many these days.