Lots of us used to run 1” climbing spec tubular webbing as bridges when the Sit & Drag first got really discovered. Heck, I ran one until a year and a half ago. My favorite part of using one was being able to adjust it to find my optimum length. Make sure you use a slip free knot, of course.
................................................................................All climbing methods, platforms, saddle designs, and/or use of materials possibly mentioned in the post above are not peer reviewed for safety, and should only be used as an example of my own method. Do your own research and testing before becoming confident in any DIY solution to support your life.
-IkemanTx