A little off topic but it leads to some welding I'd like to do.

I recently bought a pickup truck. One of the things I'd like to do is build a cradle that slides into the trailer hitch receiver, and supports the end of my kayak that hangs over the tailgate (welding project). I just want it to take it the mile or so in my neighborhood to the water. problem is that I can not for the life of me get the hitch pulled out of the receiver. I have tried soaking it with PB blaster, beating it with a BFH, and putting lots of heat onto it. No luck. and yes, the pin is out

I thought about a big chain and a stationary object, but the chain is likely to cost nearly what the truck did, and I'm unsure of a suitable stationary object. I don't want to damage the one nice big tree in my yard. I'm also concerned that when/if it comes free, it will be a missile in the other direction. I don't live way out in the country and so safety is an issue.

Anybody have any advice?