Tips on rehabilitation

Hello everyone!

I found what I am nearly 100% is a Phidippus audax in a cooler I bought from a garage sale. I noticed his back legs are not really working and he had a difficult time walking & climbing. I moved him into a cup and am currently on transport with him home. I'm planning on setting up a small horizontal quarantine bin with a paper towel and moderate humidity. I'm also planning on keeping him somewhere dark so he can just rest and then go from there. does anybody have any tips on anything else that I could be setting up in his enclosure a little bit better and / or things that I should prepare. I will include a photo once I arrive home. I appreciate the help and thank you!