Tony, if you wanted something amphibious just go out buy a BassTracker boat and tow it with your Tracker! lol! Making your rig into a floater with propulsion isn't hard but it is time consuming and you will need several "trial-and-error" sessions to get it right. What will you need?
1. Several gallons of liquid expansion foam to fill every possible void on the rig like fenders, doors, roof, quarter panels, tailgate, etc.
2. The aforementioned barrels and tubing to mount them to the truck.
3. A snorkel in the front with an elevated exhaust pipe in the rear.
4. A thorough electronics water proofing both inside the cab (under the dashboard) as well as under the hood (bonnet for the non-Americans lol).
5. A sub-frame underneath to support steel plating from front to back (so that the rig will deflect water away and come up on plane easier).
6. Optional item: a set of outriggers to help stabilize it side to side.
The outboard size should be kept under a 90 hp or less to keep the weight balanced f/r, and to keep from overpowering the truck and taking on water. Other than that, it should work.