I'd just get something else.
Having it in there and trying to make sure that it receives less water then the others seems like to much of a hassle. Also there's no way to stop the water for seeping over onto it's side through the soil. I'd put the sanservia in its own pot and put it some where with bright light to make it happy.
I'd also actually give all the plants there own pot as they all need differnt soil and water requirements and eventually one will choke out the other
But pothos and Spiders should be OK together
For other companion plants have you consider other species and variations of both pothos and Spiders? There's a lot out there and most have the same requirements....

Suggestion: Replace the soil where you want to plant the snake plant with very fast draining. Snake plants can actually tolerate a lot more water than people think.

Alternatively pot up your plants separately in appropriate mixes and just use the window box as a cache pot. Then you'll have what looks like a combined planting but you can treat them separately.