It is not the shocks that keep the car from "tail dragging", it is the springs and suspension systems.

Several things that are more important to consider than springs are brakes, rear axle (transaxle in front engine front wheel drive cars.), and transmission.

The swept brake area of your braking system determines the weight your car can stop within a given distance. Even with the best brake shoes, if you overload the brakes, they can heat up, glaze the pads, or distort the disk or drum.

Rear axles that are designed for a certain weight occasionally can strip gears if run at maximum weight continuosly as can transaxles. Universal joints on the drive shaft can snap from the above stated type of usage.

Transmissions can overheat from constant high weight use, boil the tranny fluid and gum up an automatic or glaze the friction pad on a manual tranny.

Your best bet is to modify your car with larger brake swept area if possible, and use it at 1/2 or less GVWR to cut down on potential problems in the back country, or buy a larger vehicle with a small engine.

If you are really worried about a "Bug Out" situation, I would recommend a Rokon or similar bike with trailer hauling capabilities (with the trailer having enclosed, safety belt, & roll bar equipped seating.). With such a unit, you could carry a spare motor and drive assembly right in the trailer, with your biggest limitation being speed, and your greatest assets being fuel economy and versatility.

Good luck.

Bountyhunter