Here/s an inexpensive bed extender from Harbor Freight. The only problem is, like most bed extenders, it has a squared off bottom which tends to drag across ravines, etc. We solved this problem by cutting and re-angling the bottom as shown here. There are a couple of brands that you can buy already built that way. It's an important consideration unless you have a raised truck (or lots of clearance). If you get one like that, avoid one that lacks an adjustable height though -- that's an important consideration.
Most bed extenders can also be flipped to support overhead lifts like this:
The PA 14 will fit a 6 foot bed with or without a bed extender, but the extender is a more secure way to transport. Here's what it looks like both ways:
