Thank you for contacting us! Considering all components from both kits are the same excluding the actual SumoSprings, that’s a great question. We actually recently had someone call us to let us know that an he had the SSR-180-54-1 on his 18K chassis. He described his experience as “very harsh and undriveable.”
Reason being, is the -54 (yellow) density has just too much of a spring rate for an 18k chassis. That chassis wasn’t heavy enough to compress the SumoSprings, causing the rough ride.
I definitely recommend to stick with the SSR-184-40-1 for your motorhome as well. The SSA41 is usually meant to be installed on one side or the other, for motorhomes leaning to just one side. If that’s not the case, once again, I recommend going with the SSR-184-40-1.