Well as mentioned Cowboy's Sweetheart would be a good one (That is the title
btw) also some others to consider are two seated saddle, one gaited hoss, and
the old Gene Autry tune ridin double. Montana Cowboy is another good one (change
the location as desired) you could switch the words around on arms of my love by
Riders in the Sky and make it into a tune from a girl's perspective. any number
of ideas :-)
whatever you choose, get video and post on youtube for the rest of us.