The Eagle was a fairly common sight here in Maine when I was growing up- but unfortunately not quite as common as the aforementioned Subaru. I think the real market for this "crossover" (ugh, can't believe I used that phrase) was the same then as it is now, and the Eagle just didn't have the yuppie cred. What it did have was a rugged I6 and a body that didn't disintegrate within minutes of hitting the carlot- but I think those customers probably were more likely to buy a Wagoneer.
I'd buy a '59 DeSoto wagon and a Sawzall.
Limited to the choices at hand, definitely the El Camino. Heck, you could always beef up the suspension after the fact.