If you're going to be installing anything in adverse environments or for any period of time PLCs are the go-to for a lot of one-off solutions. Some of them get pretty spendy quickly but Automation Direct has some reasonable($100-200) PLCs[1]. I ended up automating our entire greenhouse with one including a PID based water pump to drive a bunch of different downstream outputs that worked really well.

[1] https://www.automationdirect.com/adc/overview/catalog/progra...