No, the tank wouldnt fit between the beams after I installed my gas line. I would have had to reroute the gas line which would include obtaining a die set and threading the pipe after I cut it out.  The tank sits highter than the axle and the walls are 1/4″ thick so well see how well it will hold up. As far as drainage, there is a about a 31″ rise from sink to the top of the tank so water will drain even if a bit out of level.
 
I bought this tank back in december off of ebay cause it was a good deal. I would prefer to have the same style tank as my fresh water tank but there are plenty other things that I need to buy still to get this completed so I’m just making due and even with getting the other style tank, I would only gain like 2 inches or 3 inches in depth. 
 
 

Couldn’t you get that tank between the beams??….That looks like an accident waiting to happen.
I also would have plumbed the waste directly into the tank, if your just a bit out of level on the one side, your going to have problems draining……..