SERIOUSLY??? Another Broken Grey Tank Drain???

Many thanks to @Oinfront for this thread and their other shower drain thread. We have a new-to-us 2019 400 and while it is in generally excellent, barely used condition, we have spent the past several days discovering that not one, not two, but all THREE drain connections to our grey tank are broken. In the same manner as described by everyone else here. With all the info we've collected here, the repairs to the shower and galley sink are straight forward. thank you @Oinfront and everyone!

BUT, the bathroom sink drain appears to be completely unreachable. I haven't found anyone whom has had to deal with that repair. We are happy to forget about bathroom sink and not use it, but we need to address the open hole in the top of the tank so we are not leaking from the tank. We are considering three painful options. 1) drain the brand new glycol from alde (that we replaced 48 hours ago) in order to remove the heating register under the bathroom which is blocking access to the broken drain. Even so, we still might not be able to get deep enough in that small space to make the repair. 2) remove the grey tank from the frame in order to seal up that inlet forever. 3) pay a lot of money to a dealership to make the repair.

We are capable of doing it ourselves so there is little chance we will pay a dealer. We are just trying to determine the least of the bad options.

I'd love some opinions if anyone has experience with this challenge and/or removing the tank.

We knew the purchase price was too good to be true and now we know why!