Get the Garmin 760 or newer and be done with it. Do the updates every couple of months.
I use mine in both the MH and the toad. If you do that, remember to change the setting from MH to a car when you turn it on. If you leave it set on MH and you're driving the car, it will think you are still in the MH and will probably route you differently than if it were set for a car. This will especially happen when in a congested area where the car can easily travel but the MH can't go in certain spots.
Then set it back to MH when turning it on in the MH.
Bill