You might want to try a yoga block(s). https://www.walmart.com/browse/sports-outdoors/yoga-blocks/4125_4134_1078384_1078393
You can cut a V or U into the block and cover it with scrap leather. They are about the size of a sandbag but much lighter.
I copied from a listed review on a web page. Also make sure the card is inserted correctly. I mention that only because a friend had problems with a phone when he did it incorrectly. https://www.dpreview.com/articles/7534542931/konicaminoltaz5
A guitar is easier to pawn than a gun. Guitars can be worth way more than any gun. A saddle blanket would be a way better cover, especially if one ever scented a used one.