Welcome to the nest first off and to answer your questions ....... Deep sand i don't know personally but you can make an eagle for whatever he terrain depending upon how determined you are to get it there.As far as models to look for is depending on how many people/ stuff you want to haul, at the moment I am the proud owner of a wagon (my daily driver when it is not needing repairs), a SX/4 that i am going to be restoring, and I will be the official owner of a Kammback today (I love all of the eagle models). Wagons are the easiest models to find.
When you are looking at an eagle to purchase as a driver prepare to be on the ground, look at the frame sections (behind the tires is the major spot), check the lines for rust (gas and brake lines run down the passenger side if they look really rusty plain on replacing them) look at the rockers (there are currently replacement outerrocker panels available), check the floors, check all of the bushings in the front suspension, look under the hood to see if there are any loose vacuum lines (this can cause the car to run poorly, not pass an emissions test, and not idle), check for aluminum valve cover (87 and 88 cars come from the factory with them, others have a leak prone plastic valve cover that you will end up replacing)
And as far as cars for sale. At the moment I know of 2 SX/4s for sale in southern Pennsylvania, possibly more (send me a message if you are interested)
Happy hunting