Might want to check on if you need to update/ change your ECU program to have it work with the gear change. Shift points could be off, as well as speedo.
As far as towing goes I've only towed mine back from up north. IMO the V splits the wind down each side of the trailer, when you pass or are being passed by someone it effects the wind distribution and seems to push you around a bit. Could just be or my truck/trailer combo as prior to this one I've only towed gooseneck style enclosed trailer.
One thing I did do was to tie the galley tank into the output of the grey tank so only have to hook up one hose. Not easy finding the black ABS fittings and piping, but a good RV shop will have what you need if you decide to do. Since it was a long run I installed a flexible coupler. Was afraid it might crack the tank or line going done the road.