[oem4me]

Forstner bits are great, but an easier to find and cheaper alternative would be a spade bit. Either way, you'll need to determine where the bolt hole needs to be first, pre-drill that hole with a small diameter twist drill (1/8" or less), then mark where the offset should be. Obviously, the centers will not be the same. Bore the large shallow recess with the forstner or spade, then follow by chasing the small pilot hole with proper size for the bed to chassis bolt.