This is not necessarily about splash-back, but I felt like I'd mention it here anyway (and it might help a bit with splash-back). I recently got a product called the Squatty Potty and I am a big fan. It's a deal that props your feet up while you are crapping to encourage full release. It has cut my crapping time in half. I recommend it. I got mine for about $28 off Amazon.
^^^^^ Good, but not good enough! Dang breh, I feel sorry for you! You do seem to have quite a situation on you hands, and if left unattended can cause irreparable damage to your psyche! Luckily there is a solution! This product was invented especially for people such as yourself.... Spoiler Your dreams have finally come true.... No more backsplash on your rear end!! ....... ....... .......