I very very rarely work by the hour because if you do that is all you are going to make, but i cost my tracked machine out at minimum 110 /hr.
Towing 12-13k with a half ton is pretty crazy. I dont want to discourage you but not only is it extremely hard on your 1/2 tonne that is rated to tow half that weight, it is very very dangerous. If you happen to get into an accident and your insurance finds out , you will be in one heck of a law suit from them and the person you hurt.
Might be best to get the proper truck before you get the machine. In the end it will save you a lot of head aches and $$$