I expect that the Maine Eastern schedules may change when the DE connections are added, but at the moment the Maine Eastern schedules are very Rockland oriented.
If you wish to start from Rockland, the train departs Rockland at 0750, arrives Wiscasset at 0900, and arrives Brunswick 0945. It departs Brunswick at 1030, arrives Wiscasset 1115, and arrives back in Rockland at 1225. Thus, there are 2 hours and 15 minutes available in Wiscasset for a side trip for those coming from Rockland. (In the evening, the train departs Rockland at 1555 and arrives Wiscasset at 1705, well after we have ceased operations for the day.)
If you wish to start from Brunswick, the train departs Brunswick at 1030, arrives Wiscasset at 1115, and arrives Rockland at 1225. It departs Rockland at 1555, arrives Wiscasset at 1705, and returns to Brunswick at 1750. Thus, there are 5 hours and 50 minutes available in Wiscasset for a side trip for those coming from Brunswick.