Buster,
Without more research, I am not sure I can give you a concrete answer. I KNOW that air bags help raise ride height-- in other words they "lift" the coach all the time.
I don't know that the Timbren SES works the same way. It may be that they are more like "overload springs". In other words, that they only work when the existing springs are further compresses. This would act as additional spring rate on compression, but NOT raise ride height.
Look forward to hearing from someone with more experience with them.