Tank pan removal on '78

[mdroppo]

I have a '78 with rear bath. I have been working on it and
there is a rank smell coming out of one of the round flexible ducts that goes under the floor. I've tried blowing it out, draining and rinsing the tanks etc. There were rodent droppings in the trailer when i bought it and am afraid his little corpse may still be with me. Or maybe there was/is a black water tank issue. I want to get up underneath to see what's up in there. The rear tank pan looks like it will just come off by removing a bunch of bolts. I would like to take it off and see what everything looks like in there. we're planning to full-time for the next year and write a book. It would e a great piece of mind to know everything about the trailer. has anyone done what I'm talking about, and if so how much work am i in for not only taking it off, but putting it back on. Any advice would be very appreciated.
Thanks,