Domicile is probably the first thing to sort out. Will your husbands official work station still be in MD? If yes and you can't change it, you are probably going to pay MD state income taxes.
If you can move it, you can pick a state that is beneficial (such as one without a state income tax).
It's also possible to pick a state that has conducive home schooling rules.
The 18mon old should be any more of a handful than if he was in a house. Remember, you likely aren't doing 18hr drives for days on end. We rarely travel more than 150-200miles in a day and often under 100miles. Once set up, it's just as easy to keep an eye on the kids.
As far as appointments...you can always plan to swing thru MD or get a doctor in an area you do plan to swing thru on a semi-regular basis.
