My advice
If you must make it work with your f150, I say get a trailer.
I have a 12'x8' single axle trailer, it weighs about 800lbs empty (It was my first peice of equipment). I can cram a ton(or more) of slash in there and all I need to do to unload it is throw a rope across the trailer before I load it, tie a running bowline around the slash, and then tie a bowline around something at the dump, drive forward til the slash comes out, push it back a bit with the truck/trailer, untie the rope, and I'm on my way. Usually I am in and out of the dump in under 15 minutes and it costs me $30 or less in dump fees. Or I can lie and say it's from my house in the city - then its free, but i try not to do that too often!
I got my trailer for $1000 new (this was 6 years ago, might be a bit more now). You could probably tow something like a 14' double axle trailer with an F150 - put some high sides on it and cram maybe 5000lbs of slash in there!
Nice thing about a trailer is; towing 3000 lbs is much easier on your truck then hauling 3000lbs in the bed of your truck. Thats about what a full load of chips in a long box with 4' sides weighs - 3000lbs. Plus you still have the bed of your truck for tools!
I currently use a 1 ton landscape dump with plywood sides, a big 16" chuck and duck chipper for every job, plus a 3/4 ton pickup and my old trusty trailer for hauling wood on removals. The trailer still comes in handy for hauling slash on certain jobs - like juniper bush removals.
Even Small 12" chuck and duck chippers weigh close to 4000 lbs - thats gonna feel pretty heavy even when your truck is empty. When you have a full load of chips you better drive really slow and leave your self plenty of time to stop.
As far as the 6" vermeer, I would say save your money and put it towards something more productive.
Everybodies circumstances are different. It depends on how you can effeciently dispose of chips/slash. Good luck and make sure you have fun with it!
wow that was too long