I have had Gabriel Hi-Jackers on my '70 Monaco 4drht since the middle 1970s. Only about 60psi to level the car, no more. They have been great. No adverse issues with anything.
Consider, nobody advises against the load-leveler coil-over rear shocks, which can put some of the same stresses into the structure that lower-pressure air shocks might.
Consider, that each bump the car takes, the shocks resist that and THAT force goes in the structure at the same location. If something might happen, it is the upper mounts where the bolt holes might ge a bit enlarged if the bolts get a bit loose. The more HD and stiff the shock, the more pressure spikes.
One thing I did notice was that my car cornered better from the low-psressure rear air shocks. Almost like an easy-to-install rear sway bar. Air shocks for C-bodies also have the large 1 3/8" piston like the HD shocks of old, which I consider to be a plus. The base 30psi pressure will not significantly raise the car, just put enough air into the air bags to keep them inflated and unwrinkled.
The 1980 Newport I bought had some Midas-branded Monroe air shocks on it when I bought it. The prior owner wan an oil field tool company. The car also had a home-made angle iron trailer hitch on it, which I removed. It had obviously seen some off-road use and pulled trailers. No issues with the upper chock crossmember getting deformed by that use. I put new Monroe air shocks on it and they are still there, decades later. Using only 30psi in them. The probably saved the rear factory HD rear springs.
Now, in my uses, just to level the car on the Monaco, and to get the HD rear shock function on the Newport, I'm NOT using them like many did in the earlier 1970s, to let everybody see my rear axle (some with a "Peace" symbol on them) as some people did in order to look cool or as if they just had to have the widest tire available (for the look of POWER) under the back of the car without hacking it up.
If I was using those two cars like a HD2500 pickup truck, THEN I'd certainly put some heavier purpose-built springs under them. I'm not, just wanting a level car with a good HD shock on the back. No more, no less. My decades of use has proven to me that I made the correct decision.
When I bought the Monaco in 1975, it had the coil-over helper shocks on the back, as the prior owner pulled some sort of smaller trailer with it. The rear springs were/are sagged. At that time, the only spring shop was 30 miles away and getting new springs from Chrysler was not possible and more money than I wanted to spend anyway. So, air shocks were my best option. Now that new rear springs are more readily-available, I might make a different decision these days, but probably not.
From MY experiences, air shocks are not nearly as "evil" as some make them out to be. Perhaps if I was in a locale where the roads were heavily-salted in the longer winter, I might think differently. BTAIM But if I was in such locales, the rest of the cars might not be worth saving, either?
Just MY experiences and observations,
CBODY67