With this mod, custom slime hutch maps can place water troughs on any tile and they will be recognized by sprinklers, watering cans, and slimes alike.
An example mod is here: https://www.nexusmods.com/stardewvalley/mods/13779
Technical
Requires SMAPI, uses Harmony.
Compatible with Mod Updater for automatic updates.
Code is at https://github.com/aedenthorn/StardewValleyMods.
If you want to complain or ask for help or help me test my mods, you can visit my Discord server.
A list of all my mods for Stardew Valley is available at https://www.nexusmods.com/stardewvalley/articles/895.