I did exactly what is being recommended about a year ago when my transformer started getting really hot. I cut the cord, bought a nice quality accessory adapter (cigarette plug) at Radio Shack (that was fused) and plugged into the Winegard wall plate in the overhead - about 12 inches away from the AVS100HD unit. Has worked flawlessly ever since...
Good luck to you!
2008 Berkshire 360QS
with Mercedes Power
2010 Mini Cooper Convertible toad
2015 Nissan Frontier 4x4 pickup toad