My 2 cents: Medical school can be very stressful, and residency (particularly surgical residency) is even worse. Assuming you are fairly certain that your husband will get into med school, it will be a long haul with lots of expenses and no income for the first 4 years, then relatively low income through residency (Maybe $45k-50k per year with long hours and high stress), and then maybe fellowship. After that, even in the lowest paying primary care specialties, he should be making close to $200k within a couple of years out of residency, much more in certain specialties ($500k in orthopedics!?!?!?).
Before thinking about living on opposite sides of the country for 4 years, be aware that divorce rates are particularly high in surgical residencies. I don't say this to scare you, but I would guesss that being together through these experiences outweighs any added income from living in apart. Assuming you'll be working in a university (are you in a biomedical field?), there is a chance that if you get a job offer, your department chair can talk to the med school, and if he gets accepted to med school, the med school can talk to the university to see if you can get a "package deal" of offers. I know people who have done that with one spouse needing a post-doc position, and the other entering med school.
Stay frugal through medical school and you'll be fine. If you can pay tuition off as you go, that is great. That said, making over $150k after you finish makes borrowing to pay for med school (if necessary) a good return on investment as long as medicine is something you truly want to do. I'd never do it just for the money... not worth the opportunity costs.