Eco earth under the mulch would probably help. For plants, things like spider plants or pothos can handle being sat on and are pretty hardy; there are lists out there of common plants that are safe. In general you want ones that won't tip and can stand up to a bit of abuse. So avoid ones that will break if the snake tries to climb up them. Grassy or vine-y ones are good. They'll need some amount of light during the day, which I know potentially involves more rigamarole with light fixtures, although lots of the popular and hardy indoor houseplants can do fine with pretty low light - they'll just grow slowly, which is fine because you don't have unlimited space for them anyway.
But otherwise it's easier to remember to water them when they're in with an animal whose water dish needs regular attention anyway. :)