OK, old (72) raw beginner here. When I have the guitar in a "normal" position, I have trouble getting the strings to all ring out, and my left hand starts cramping. If I put the butt of the guitar on the bed and almost straight up, I can get everything to ring out very nicely, and it's comfortable. Assuming I can't take the bed with me to the campfire, what can I do to fix this? I do have short, fat fingers.

Thanks for any advice.