We were just there last week, and I wouldn’t think you would have any problem getting a spot for the next few weeks at least. I would just call ahead a few times to check their availability and go.
It’s still early spring up there, raining regularly, and I think the locals refer to this time of year as “mud season”. The black flies weren’t horrible, but they were there.
The visitors to Acadia are just starting to ramp up. The horse drawn carriages in the park weren’t running when we were there due to the muddy conditions in certain areas, but the hiking and carriage trails we went on were fine. Plenty to do in the park and local area.
:):)