Gaaahhh, I’m so sorry you’re facing this 
I was fortunate in that the week leading up to the day was great weather, it was early October. I gave Rio 2 baths, which he always loved. I got his whites white, his luxurious tail impeccably clean and detangled, let him do all the things he loved to do while getting a bath. He didn’t wear shoes, so nothing there. I did save JB’s last shoes, which were removed many months before he died, and 1 front and 1 hind are imbedded - open side in - in the concrete in the barn aisle. The other 2 shoes are used to support the shower rod or our master bath
The day of, I gave Rio his normal breakfast, and then gave him another pile of his food to eat as he pleased. I’d never actually seen him FULL LOL
I did save his magnificent tail - can’t go back and that that. I also saved his forelock. You might not be a jewelry person, but there are endless ways to use hair if you want - key chains, pottery, fly swatters, inbedded in picture frames, etc So definitely save it just in case. I cut his after he was gone. Hubby helped hold it all while I cut, and I wrapped the cut end with several big rubber bands, and it’s curled up in a plastic baggie right now, with his forelock. If you can’t bear to do that (I was surprisingly ok with it), I’m sure your vet would be happy to.
I still haven’t cleaned Rio’s stall :\ His last poops, and the last hay he didn’t finish, will go in a garden bed I’m still planning
Hugs. The time between the decision and The Day was awful for me. I was still terribly sad after, but also much more at peace with the situation because it really was the right thing. I hope that happens for you too, and you can be ok with being ok, and ok with the grief process.