Rear bath with the short toilet mounted up on a little platform?
The tank is under the platform but above the floor. Its capacity is about 8 gallons I think. May be why it's leaking. It's full and leaking out at the toilet flange. You have to remove the sink countertop, toilet, and cabinet on top of the platform to get to the tank. First I'd dump the tank, then get a new seal. Remove the toilet, replace the seal and it may fix the leak.
If the toilet sits flush on the floor the tank is below it under the floor. There is a big galvanized pan under the trailer holding it up. The pan is bolted up. Remove the bolts and pan to get to the tank from below. Still may want to remove the toilet to check from the top first before pulling the pan from below.