Maybe you could build a secure platform to help hold the ladder in place and sturdy. Keep the ladder firmly on the ground, but clamp or otherwise attach it to a frame that stands several feet high. I'm visualizing one made of 2x4s, with a 4' x 8' base (or what room you have) to give lots of stability, with a second frame 4' up from that, connected with lots of 2x4s for more stability, and all staked into the ground. You don't need a platform on top, just some crosspieces to attach to the ladder. You could also build a small box to keep at the top of the ladder to hold your tools and supplies.

Silicone tubes would be a lot easier to cut, and cheap too. I just found some food grade ones at eBay... https://www.ebay.com/itm/Food-Grade-Clear-Silicone-Rubber-Hose-Tubing-Brew-Hose-ID-0-5mm-50mm-OD-1mm-60mm/144007235098?chn=ps&var=443290852298&_trkparms=ispr=1&amdata=enc:11Z4pf3TBRqyFO1Ws2h3DRA68&norover=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=443290852298_144007235098&device=t&mktype=pla&googleloc=1018251&campaignid=17597089569&abcId=9300988&merchantid=424807978&gclid=Cj0KCQiAzeSdBhC4ARIsACj36uFFOT6v2v3GhtCNUxa3Ifc2GcGljGgDZOIQveNnICwXjzmkH4TKsf0aArCmEALw_wcB&pageci=7c238ab5-83b2-4502-8695-b12a15b904e3&redirect=mobile