I totally get the spirit of the intent....same that I had.
For me, the OEM snoopy loops on my XDeep BPW (supposedly a premium brand) were crappy inner tube, unevenly cut and inconsistently thick. I thought about doing the same as you but concluded hunting around for a quality inner tube was going to be an unnecessary level of work for likely the same outcome....crappy inner tube.
The manufactured snoopy loops are much thicker and more consistent quality. I tug on two nearly every single dive...the one on my left waist to stow the excess length of belt and the one on the right shoulder strap that keeps my back up light in place. Both look the same as the others that don’t get stretched.
I was happy to spring for a half dozen and it was easily the least expensive upgrade (and improved peace of mind) I’ve done compared to second and third iterations of fins, DSMBs, spools, lights, regs, hoses, etc, etc, etc.