I would stick with the 30 amp setup. The 50 amp plugs are sometimes hard to come by, and unless you are going to run 2 roof ac units there is no real need.
Note: some campgrounds charge more for a 50 AMP vs a 30 AMP.
Also unless you wire it to the RVIA standard the 50 amp feed could blow a pole based GFCI and have no power at all. Much simpler to just rewire it as it is and go from there. Not to mention the time saved!
WBCCI #5501 AIR # 49
1978 Argosy 28 foot Motorhome
Wise men talk because they have something to say; fools, because they have to say something. -- Plato