You could add a bulkhead and have a three-way valve between the two. Have a draw tube on the backside of the second bulkhead that goes to the front of the tank. I know from memory there have been a few occasions where it would’ve been tricky for me to get parked facing uphill.
Kind of like how I linked my two water tanks:
The elbow on the back side of your bulkhead is a really good idea for a low profile tank, as well 
As far as your dump valve goes: I would add another bulkhead off in the corner out of the way. The fewer fittings you have on your suction line, the better.
