You can check by flushing a non marking dye into the tank and watch for the colour. Even purple Kool aid would work. Also check all hose clamps. If it is the tank, they are made by a third party like Dometic for example. Just measure the existing tank to find a match.
I looked last year and couldnt find one. The best you can do is to pull it, check all the fittings and look for cracks. Possibly seal them. A replacement will have to be a generic tank that you find that fits in the space
What makes you think it is coming from the tank? If it is coming from the tank, then it would be dripping in to the bilge under your aft bed. If you have sewage there, then yes it could be your tank. Here is what I did so that I could visibly see the level of liquid in my waste and water tanks on my 06 342. You may want to do this and go from there:
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PC BYC, Holland, MI
2018 Cherokee 39RL Land Yacht (Sorry...)
https://rinkerboats.vanillacommunities.com/discussion/comment/58699#Comment_58699