If it is a crack, I dont know if you could repair that, but if it is a hole, I am thinking the answer is already in front of us. The tank sensors are mounted to the tank. They just drill a hole in the tank and stick those into the hole. Then they use some sealant or a rubber washer, etc. Could you just use a small screw and some sealant.
Especially if you can find a plastic screw (my only concern is rust). Unless you can make sure you coated the screw real good with sealant? Anyways, just a thought
2015 Rockwood Mini Lite 2504S
2015 Ford F150 Ecoboost