After reading your post, I did some perusal on the topic. Seems March may be more difficult than the usual May to September recommendations on sites.
You have probably already read these, but some links:
Dalton Highway - Wikitravel
Dalton Highway, otherwise known as the Haul Road
BLM Alaska: Dalton Highway - Frequently Asked Questions
My guess is your car is going to have a good speckling of road rash on some of the panels by the time you get back. And maybe need a new windshield.
Having done some long m'cycle and car trips, I understand the desire to 'go', but I would personally find someone else's car to do that trip in. ;>)
GL, mD