bolt or weld on rock rails?

I'm building some rails for the Jeep. What has everybody done to attach them to the frame? I was thinking I was going to weld them on but now I'm juggling it back and forth. They are built out 1 1/2" x 3/16 square with 4 x 4 x 1/4" mounting plates.

 

I think the worst part about bolting them is drilling all the holes, figure at least 3 plates/side, 4 bolt holes each, that 24 good size holes you have to drill...

 

exactly

This is how I am going to do it. I'm going to use self tapping screws to hold the plates exactly where I want them while I tack the rails to the plates. Unscrew assembly, weld completely, rescrew and then weld the plates to the frame. The screws will be enough to hold everything in position. I may even slot the holes in the plate for some adjustment.

 

Also I'll be using the old lincoln tombstone.