You can use air shocks to raise the back of the truck a little but I wouldn't recommend it as an every day solution. I had Gabriel Hi-Jackers on the back of my (stock height) 84 Ranger, mostly for load assist. They could lift the back end 4-5 inches IIRC. That said they were stiff when aired up even a little and made for a poor ride, I pretty much only inflated them when I had a load. You would be better off keeping your slight lift, and your load assist separate. Think about it this way shocks aren't meant to support weight they are only meant to dampen the shocks dealt to the suspension. If you increase the shock's ability to support weight you in turn decrease their ability to dampen those shocks.
How is your truck lowered? You say dropped 5" in the rear so I"m assuming that you have swapped to spring over axle. Based on that I'd recommend the chevy lowering shackles, they will provide approximately 1 or 2 inches of lift on a Ranger depending on which setting you use. Then use a load assist bag as low~n~blue mentioned. You are better off keeping the drop shocks and the load assist separate.
I'm currently in the process (very slow process) of building an 86 Ranger with a drop similar to what you have. I am running DJM beams in front, and an Explorer axle in the rear. The axle got me a 5"+ drop in the rear, but I'm also using the explorer's springs which are a little softer I think. Then I'm using the Chevy shackle to raise the rear back up about 2 inches to match with the front. Still not sure if it'll be enough because I prefer a little rake to being level, I do have a set of 2" drop springs for the front is it's not. I plan to use load assist bags if I need them for towing hauling purposes.
For shocks you'll have to do some research for that. I think most people run a Nissan Hardbody Shock for drops in the range of 3 to 5 inches. If you do decide to go with air shocks this is probably what you'll need to get them for. On my swap I'm going to run a completely different shock set-up from stock and what you have so the shocks that work for me won't work for you. I'll be copying the Explorer's shock mounting design with a shock cross member mounted forward of the axle, and the lower end of the shocks at the explorer spring plates. It'll also be set-up to use stock length Ranger shocks rather than drop shocks.