Just wanted to post a reply here, I know it is an older thread, but an Astro Van makes a great overland rig, and a very capable off-roader.
I sit 7" above stock height, I run 31x1050 A/T tires.
To answer the questions above:
1.) Put larger HD leaf springs in the back(I have drop shackles and HD springs out of an s10 Pickup) Upfront, I have Re-Indexed Torsion Keys.
2.) Easy to stick a dual battery setup into, I have an optima yellowtop, and have never ran out of power(I have flashing strobes, and constantly play music while parked)
3.) You can easily swap in a 2speed transfer case from a Blazer which would give you low range.
4.) Once the lift is installed you can go with larger tires with only minimum modification to the wheel wells, I gained an increase of 2" from the tires, and I relocated my upper ball joints from the top of the A-Arm to below the A-Arm, Put in 2" body pucks up front, and Re-Indexed Torsion keys, I have 5" of lift up front and 6" in back, plus the tires which gave me 2" more. So the front sits 7" over stock height, Plus I trimmed the bottom of my front bumper which gave me better approach angles
So to answer the question: An Astro van is an awesome overlanding platform, done for relatively low cost.
So I included a few pics