You really need to determine what the limits of your use will be. If you will not be doing any recoveries then you do not need the booms & winch that a wrecker has, all you would need is a wheel lift. I would not go with a pickup type wheel lift though, while you may find them cheapest I would believe that this is not an area to skimp on as it will just wear out if not designed well.
You may be able to get a used wheel lift from a wrecked wrecker.
or if you look you can find a full bed for a decent price. Ebay has four from $1500 to $2500 for the full bed w/wheel lift, winch, and boom. Everything you would need. They are in TN,NY, & CA ... if you keep watching stuff shows up relatively close eventually. Keep an eye on Craigslist as well.
You also said you have a lot of equipment for fabrication, you could make your own wheel lift to your own specs. You would need engineering knowledge(actual schooling) to design it safely though.
Last thing to consider(or perhaps first) would be to call your insurance agent and see what it will cost you to run your truck. You may also want to call the State Patrol and run the idea by them to see what commercial vehicle requirements you will now fall under. There may be a lot more involved to be legal.
Tad
