This is one of those not-what-you-asked responses, but I hope it helps shed some light on what I think you're getting at.
The AHC spring rate is a combination of the straight, mechanical spring rate and the progressive gas spring rate of the compressed nitrogen in the globes. Assuming everything is in working order, you really only need to keep the system within the right pressure range for it to function properly.
That being said, in the case of the rear suspension, every additional 200lbs over the rear axle will increase the pressure by 1MPa with stock AHC springs (90lb/in rate). As an example, the King KTRS-79 springs (130lb/in rate) will lower the pressure by 3MPa. That's the equivalent of an additional 600lbs over the rear axle. The 80 series and 100LC springs are 150lb/in and 170lb/in respectively. I'll let you do the math on how much additional weight you would need to be carrying to get the system back into spec. Add to that the fact that new OEM globes will have a higher pressure gas charge than old ones, and aftermarket Citroen globes will have a higher pressure gas charge than new OEM and you can see that it's easy to end up with an oversprung suspension pretty easily if you go down that path.
For the front, you run into additional challenges because the gas spring and torsion bars work in series (instead of parallel, like the rear) and there's no available happy-medium between the AHC 25mm bars and the LC 28mm. However, the adjustable pre-load of the stock AHC bars and the variable damping range of the AHC system allows proper damping even if the front is slightly undersprung. It'd be ideal if someone made a 26.5mm t-bar, though.
To bring all that into perspective, I run steel skids, sliders, steel front bumper, winch, roof rack and a family of five with all the associated crap that comes with us and I run stock t-bars (cranked and re-indexed) and King rear springs. My pressures are 6.7 (F) and 5.6 (R).