My brother just did an oil submerged rig, and yes, it is a HUGE headache.
Not all hardware is "oil ready" too, so you might just waste money on that aspect.
Plus the oil does warm up over time, and it can really screw with your CPU and cause random shut-downs. We added an over sized aerator which definitely helps keep it cooler but it also makes quite a bit of noise, though it's low so it's good background noise.
And also, yes it is QUITE a pain if something goes wrong or you need to do any work on it. Cleaning towels got old real fast.
Has the project been worth it? No not really. Modern CPU hardware is typically designed to stay open-air with conventional fans and heatsinks, and that's how it's most stable.
Just get liquid cooled heatsinks if you want to do something really fancy.