Congrats on your purchase. Regarding upgrading the mirror, I've done this on another car and the key to an easy job is to first consult the Routan's wiring diagram and/or check inside the door to see if the required connector for the SEL mirror is present on your SE. I suspect it is, as it would be more expensive for Chryco to have two different harnesses.
If you find the wiring is there, I would scour the web for a discounted new or a good used set of mirrors - there should be plenty of 2008 and up Chrysler, Dodge and VW vans out there with the auto-dimmable mirrors. The SEL Premium mirror should be the same as the Chrysler T&C Limited unit.
Good luck, and, if you do the upgrade, post pictures.