I'd research the design and certification aspects before allowing anyone to weld on your chassis. (Although, people may laugh at that considering the quality of the original Jeep welding.)
Remember the "only as strong as the weakest link rule". If your weakest link is the chassis in the event of a heavy impact on a rock or the like, it could twist, break or crack it.
I'd rather repair a body sill dent or bent rock slider than have to contend with a damaged chassis.
May be some legal issues with the install as well.
Not saying not to go ahead, just research it first.
I have a Blackjack set which are mounted from the body mounts. The thing is, if it gets pushed up into the body, it is designed with a full length of box section just below the body sill, but not touching.
This will distribute the impact (and probably already has at times) over the entire length of the sill reducing the chance of denting the body.
The box section also strengthens the actual rock slider.
Unfortunately, I don't think Blackjack is making this stuff any more.