Someone I work with (a software engineer former hippie) is selling his house, and is going to quit / retire from his job and drive around the country in his motor home with his wife. I want to get him a going-away gift. I thought a CD with songs on it like “Going Mobile” would be fun. Do you know of any such compilations? He has a good sense of humor. 
Why not just make your own? Here are a few suggestions:
Hit The Road Jack - Ray Charles
The Road Goes On Forever (and the party never ends) - Robert Earl Keen Jr.
God Bless Our Mobile Home - Steve Goodman
Your Trailer Or Mine? - Honky Tonk Confidential
On the Road Again – Willie Nelson (for a guy with a good sense of humor, see if you can find the Alvin and The Chipmunks version)
Turn the Page – Bob Seger
I’m Leavin’ Now – Johnny Cash
http://www.artofthemix.org/FindAMix/GetContents.asp?strMixID=66435
Here’s a link to a road-trip mix I made. It’s good to listen to when you’re on the road, even though not every song explicitly talks about travel. The Jimmy Buffett track in particular is a classic.
Hijack: I grew up just across the Delaware line from Ocean City, Maryland - the town, not the user.
Betheny Beach, huh? Nice little town. George Thurgood country. I take the kids up to Betheny when I want to get away from the crowds.
Um, what sort of music would this guy like?
“Roadrunner” – The Modern Lovers
“Roads Girdle the Globe” – XTC
“Like a Rolling Stone,” “From a Buick 6,” and “Highway 61 Revisited” – Bob Dylan
“Nowhere Man,” “Daytripper” – The Beatles
“Reckless Driver” – Timbuk 3
“Travelling Man” – The Woodentops
“Heaven is a Truck,” “Roll With the Wind” – Pavement
“Driving” – The Kinks
“Runaround” – Blues Traveller
“Drive” – The Cars
and most of David Bowie’s Lodger LP, come to think about it…
Time to wander - Mary McCaslin 
Other possibilities:
Diamonds on my Windshield - Tom Waits
Shiver me timbers - Tom Waits
Ol '55 - Tom Waits
Your good thing is about to end - Bonnie Raitt
My opening farewell - Bonnie Raitt
Drift away - Dobie Gray
Can’t find my way home - Blind Faith
Do what you like - Blind Faith
You better move on - Arthur Alexander
Born to run - Springsteen
Darlington County - Springsteen
State Trooper - Springsteen
When you see a chance - Steve Winwood
I shall be released - Joan Baez
Restless farewell - Joan Baez
Drive South - John Hiatt
Tennessee Plates - also John Hiatt
“Travelling Band” – Creedence Clearwater Revival
Rig Rock Deluxe is a good place to start… at the very least it contains the essential road song, Looking At The World Through A Windshield, as performed by Son Volt.
Promised Land - Grateful Dead
Hot Rod Lincoln - Commander Cody.
Anything by Van Morrison. I also like dub reggae while on the highway.
Keep Yourself Alive - Queen
I’m going to one-up the “Roadrunner” suggestion by replacing it with the Sex Pistols’ cover.
Also, “Autobahn” by Kraftwerk.
And anything by the Clash.
“Endless Grey Ribbon,” Nick Lowe
“18 Wheels and a Crowbar,” BR5-49
“Mercury Blues,” David Lindley
I don’t know how many of my suggestions are appropriate for driving an RV, but when I drive a car, here are some songs I like to hear:
“America” - Simon & Garfunkel
“Crazy Train” - Ozzy Osbourne
Just about all of Van Halen’s first album, along with “Panama.”
Suggestions so far are all very much in the “classic rocK” genre, but a couple more recent songs I really like driving to:
“Neighborhood #3 (Power Out)” - Arcade Fire
“Southside” - Moby
“Sabotage” and “Looking Down The Barrel of a Gun” - Beastie Boys