Cheapest way to get an inch or 2...

I have to say, back in the day I knew lots of people who ran air shocks. They drove on rough Indiana roads (including dirt!), absolutely abused the cars, yet not a one broke anything on the frame or shock plates. That's GM, FoMoCo, and Mopars. Hell, some of them even rode pretty good ( a '67 Dodge Monaco 500 comes to mind!).