Torklift fronts and Happijac rear?

The front two mount points (nearer center of gravity) is all you need to hold the TC secure from wobbling out… up to a point. That point is rarely encountered; it is the point the forces of tilting out are enough to bend the Torklift mounts or the truck frame, or pull the tie-down points out of the camper.

Having the rear tied down doubles the strength.

Attaching to the bumper instead of the frame is only as good as how much the bumper can resist twisting or bending under the tilting loads.

Bouncing down off-road trails, or extreme highway maneuvers or other unforeseen events is what it takes to stress these points.

The other thing these mounts accomplish is to secure the load fore/aft. Torklift will suggest that the angle of the front chain to the rear chain oppose each other (one pulls camper forward, the other pulls the camper to the rear). Can you do this with the bumper mount?

Considering a bumper I would compare the steel bumper to the 2 inch square tube of any/all the aftermarket frame mounts. Which is stronger, a 2 inch tube or a 7 inch tall steel c-shaped bumper? This assumes that the "button" is not the weak link.

Also, along these lines, what component do you want to fail first if things do go south? Namely, your bumper or some attachment that is held in with a pin? Likely the Torklift insert is the cheapest and most easy to replace.

The benefit of the Torklift is that there is a level of protection for the truck.

The Torklift attachment point for the chain seems to have a built-in break point. I have not heard an answer for this, but where the chain attaches has a slit instead of a closed continuos hole. This slit would seem to be intended to let the chain/hook rip out under a pre-calculated amount of tension. Here is the weak link.

I think, that yes, the buttons are just fine under more than 99% of all situations, and even more suited for lighter TCs. If you have a particularity heavy TC I would settle for nothing less than a well-built frame mounting system on all 4 corners though.

For the Lance 820 I see weights ranging from 2,400 to 2,800 lbs dry, which means add another 600-1,000lbs for it loaded and wet. That would be on the middle to heavy side, though some TC can approach 5k…

I had that setup on my 2008 Silverado with a relatively small
Lance 915 and an Outfitter Apex 8.
It worked fine in the 7 years I ran this setup. There was no problem, except that the quality of the chrome on the HJ buttons wasn't great.
Drilling holes into the new Chevy rear bumper was not so nice. And I always had my doubts about the stability of the bumper. But never a problem, even in a few hairy situations.
On the new Truck, I have Torklift mounts front and rear for peace of mind.

Rear buttons bolt to the bumper?
Having factory hitch, I fabricated tie-downs similar to Torklift rears.
Having some scrap material already, I had only spend $6 on big washers.

That is what I have, and it has worked great.