I had a look at the '97 service manual and GI-39 suggests lifting the truck with a garage jack from the middle of the rear axle and the middle of the front crossmember (not the one under the tranny, the one in line with the front LCA bushings). Looks like there's even a half-circle cutout in the skid plate to make this easy. The manual suggests using a rubber or wood block between the jack stands and the sort-of-frame, but doesn't say anything about a block or pad on the jack itself.
And no, I wouldn't jack from the crossmember under the trans. Like you said, you'd be lifting most of the truck, and the line drawing in the manual doesn't make it look especially stout.