I have been gathering the forces for this, on and off for some time. It’s an off shoot of another peripatetic project, the contemporaneous Lower and Upper Canadian Rebellions.
Figures? For the British I bought the Studio Miniatures British in greatcoats from their Afghan range. They are rather 2 dimensional and frankly not my favourite items. I’m intending to replace them with the Iron Duke miniatures once (if?) they expand the range.
For the civilian loggers on both sides and the Maine posse I’ll just reuse what I have for the Canadian rebellions, a mix of Brigade Games mountain men, Empress New Zealand Wars, the odd Artizan figure and some odds and sods converted from other ranges. There are some useful FIW French Canadians in capotes from North Star, Brigade Games and Front Rank that can be used for both Canadian rebels and conceivably the Aroostook War.
For Maine Militia I have a mix of Artizan and Boothill Miniatures from their respective Alamo ranges in roundabouts and the old pinwheel caps. Regulars could conceivably come from either the Boothill deserters or Old Glory. I haven’t purchased either as yet.
Perry do period suitable Royal Marines if you fancy expanding the war. A small unit featured in the Battle of the Windmill against the Hunter Patriots so without stretching things too far you could utilise them as well.
Rules? Because it’s likely, at least initially, for actions to have been relatively small scale, I’m going with Sharp Practice, which you can scale up or down anyway.
Must have terrain? Wooden blockhouses, very similar in style to FIW ones. I’m planning on scratch building one myself but there are commercial models out there.
Hope that helps.