Aux Shock Replacement

Hey there my friends!

I have a question on the Aux Shock. As Lee knows, I've replaced the original spring on the shock with the Heavy Duty. Well it works, but I still would like to get more lift as it were. I recently purchased a BunkHouse and I've built a trailer hitch that works better for it. The question I have is this.

I'm thinking about taking the shock to an autoparts store to see if I can find an Air Shock that will take its place. I have to take it out anyway to adjust it so I thought I would look in to this. The frame, according to Lee, will not support Air Bags, so I'm thinking about the next best thing. So folks, I'm looking for input on this.

Thanks in advance folks...

Been over a month, no pics, no details as to what you ride ride? Hard to offer suggestions.