I went to Walmart and paid $5 for a roll up yoga mat, and an $8 acrylic blanket. The mat was easy to hose off afterwards. It also didn’t allow the damp ground to seep through.
Bring a blanket to bunch up under your chest when you’re prone, it helps.
There were people with really nice looking camo roll up mats with a shoulder strap, not a lot of cushion, and 2 hours in, they were damp, and their elbows were sore.
You could use your Amazon credit on the stuff below, urethane foam stuffing, link below is more than enough, pretty certain they also have it at Walmart. I had some at work.
Cut it and dry fit it to your stock for a good cheek weld, wrap it up with the tape, it’s the same material you can get in the Ace Bandage section at any pharmacy.
It’ll take a couple adjustments, but when you get it right, it’s like a custom fit rifle.
GEAR AID Camo Form Self-Cling and Reusable Camouflage Wrap, 2” x 144” Roll https://www.amazon.com/dp/B005ZTZU1A/ref=cm_sw_r_cp_api_glt_i_HE2P22GDDG1MVP6THYTV
GoTo Foam 1" Height x 18" Width x 18" Length 44ILD (Firm) Upholstery Cushion Made in USA https://www.amazon.com/dp/B07THQM9QY/ref=cm_sw_r_cp_api_glt_i_BWS1B2Q9QTWPG5SDNRFZ?_encoding=UTF8&psc=1