When our '97 T&C was diagnosed with a corroded-thru evaporator, and I found that the only way was to pull the entire dash, it was a quick decision to let a shop do the work. From what I see here, it was $700 well-spent. As I recall, the dealer wanted a lot more than $700 (I went with a recommended shop). The guy said they had done many of these evaporator jobs on fleet vehicles. It's common for condensation to settle in the bottom (poor drainage) and rust it out.
No way could I do that in 12 hours! You must be quite organized.
Our current '00 GVoyager had leaking A/C condensers (both main and aux/rear). After I replaced those, I was literally holding my breath when we tried pulling a vacuum. My nightmare was putting money into condensers, only to find out the evaporator was bad, too. But I was relieved.
2000 Chrysler Grand Voyager SE (3.3L Flex Fuel "G")
Purchased January 2008 @ 80,000 miles
Options: 2nd row buckets, rear A/C
Mods: Full upgrade to 8-speaker Infinity audio; hitch, wiring, brake controller, sway controller, & WDH kit for towing 3000 lb popup camper
R&R: 1 front & 1 rear hub/bearing, front sway bar bushings & endlinks, 1 outer tierod end, trans-shift solenoid pack, main & aux/rear A/C condensers