IIRC you need to remove the rear hitch plate and the tank will come out.
Your leak is probably from the low fuel sending unit grommet part #735-0699. Cub wants about $15 for it but I hear this one fits too and is half the price.
https://www.amazon.com/dp/B019WENJHU...hkgjyiaQsigcdQ
While you have the fender pan off too, do the fuel pickup bushing. This is part #935-0149.
https://www.amazon.com/735-0149-935-...n%2C127&sr=1-3