Here's a link to an airbag suspension kit. It's the only one on the market that I know of, and I don't know of anyone who has done it. There is no one that makes lowering coils for the D-C-R trio, and the only other way is to cut the coils, as some have done (Dodge Caravans). Or your local truck airbag shop can fabricate an airbag setup for the rear only. Here's the link to the complete airbag kit: http://www.airbagit.com/Air-Suspensi...od-14-kit3.htm
This company manufactures their own front airbag strut, which is the key to the kit, as there is no other way to lower the front end, except by cutting the coils, in which case you have to be perfect so the ride height matches from side to side. My van is a handicap van, so I've been looking for a way to lower it. But I thought $3k was a bit steep for a van we plan on trading in in 2 years.
PS: My Routan is a Calla Lily white SE w/RSE 2010