I dunno how much I would reccomend welding the front.  I would leave the front open. 

If you weld the rear, take it to someone that knows what theyre doing.  Its not as easy as everyone thinks.  But then again, if you understand how to do it then it isn't that difficult either.

I woulda turned on the ARB compressor, waited a minute or two for the pressure in the tank to get up to 100 PSI, put her in 4WD, locked the hubs, hit the ARB Locker switches, and DRIVEN out of that hole.

Create a fulcrum point on the last solid bit of ground before the hole with a couple of 2x8's, jam them under the sides until they are under your frame......tie off a strap to your bumper and one of the trees behind you so you dont lose it forward into the hole if something gives way......open the tailgate and load bags of concrete into the drivers rear corner until your rear tires are solid, should lift your front wheel out of hole using the wood under your frame as a fulcrum point and give you rear traction.

http://www.theforgottentechnology.com/Page1.htm

see this guys site for a better idea of fulcrums and moving large objects by hand.

rkteckt-
     Thanks for that link. It kept me busy for about an hour! It's amazing what a retired tradesman can do to show intellectuals how things work! Have a good one!

I woulda turned on the ARB compressor, waited a minute or two for the pressure in the tank to get up to 100 PSI, put her in 4WD, locked the hubs, hit the ARB Locker switches, and DRIVEN out of that hole.

Show off. 

That forgotten tech guy is a riot, im almost tempted to buy his dvd so he will keep making bigger rocks and moving them around his yard......


As far as the sink hole goes, i have a sammy so i would have just tied some balloons to the bull bar and lofted it to safety