Have stayed twice at the park both times we stayed one week at the Rio Grand Village RV park (full hookups) to see the east side of the park and then one week at Maverick Ranch RV Park in Lajitas to see the west -again with full hookups - its a very nice park with a beautiful pool for the kids, we have checked out them all on the west side of the park and its the best.
Internet and cell in the park is not great - my Verizon air card would not work in the campground - they did have service by the office - Verizon cell works on the hill about 2-3 miles from the campground towards Panther Junction
We just were at both this past March - there are any number of great 4X4 unpaved roads that you will enjoy - we took one about every day
Take your passports and go to Mexico - take the international ferry (rowboat) over it was great - we had breakfast at a restaurant over looking the Rio Grande

