Have a GREAT time! Grand kids are wonderful! As a friend once advised me, "their teeth can't rot out nor can they die of malnutrition in one day - so spoil them as much as you want, it's their parent's job to ensure no ill effects!"
I have the (older version) Garmin 760RV and mounted it in the dash "cavity" above the radio. Wired it to the radio power (pulled the radio and spliced, think I drilled a hole to route the wire). Very satisfied with that setup (plus replaced the Magnadyne with a non-GPS Kenwood for sound quality reasons).
Regards, Jim

Great! Hope it works -
Jim

Dagodude -
Good luck with your Magnadyne. You may find getting a stand-alone GPS and just using the Magnadyne for other functions is a good solution.
For manuals, check under “Library” at the top of this forum. There are no model specific manuals. Also, check the Forest River site, think they have started posting more manuals there.
Refrigerator- most of us run with the propane and the coach 12 volt system on while driving. Some discussion on the forum of running the refrigerator off an inverter while driving - should require about a 400 watt inverter, and pull 35 or 40 amps from the House batteries while cooling (maybe 50% duty cycle after cooled down?). I have not done this - I just run on propane.
Most places that have 50 amp service also have 30amp service. That said, many of us do carry a 50 amp to 30amp adapter (RV shop, Walmart, Amazon). Sometimes the 30amp campground outlet is beat up or shows burn marks - so I use the 50 amp outlet in that circumstance.

Jim