I will be moving out to Maine (Biddeford/Portland area) for medical school and would greatly appreciate and suggestions for boarding facilities!
Call Spurwink Farm and speak with the manager there - Karen Friedlander. They have limited openings, and no indoor… But it’s a wonderful place (on the ocean in Scarborough) and Karen is a great contact to make. If her farm doesn’t work for you, she will be able to point you to the best alternatives in the area 
Tanya Rennie is in Gorham, at Vienna Farm. She’s dressage and I know people really love it there.
Karen Folan is at Trio Farm in New Gloucester. It’s north is the city but is eventing focused.
Race Me Stables is in Westbrook and may be a good all around option
I assume you will be attending UNE. What type of training/trainer are you looking for? I assume you want an indoor because Maine winters can be a challenge and you’d miss out on a lot of riding without one.
Tanya Renie’s barn is Vienna Farm in Gorham (a couple of miles past my house). She is a Grand Prix rider and has her Gold Medal. It is a dressage barn, but I expect you probably could hook up with an eventer-type also for your jumping. The farm is about 30 minutes from Biddeford, 20-25 or so from Maine Med in Portland.
Race Me in Westbrook is convenient to Portland and the turnpike from Biddeford. I know a few people who have boarded there, but I’m not sure what the situation is if you need a trainer.
New Gloucester is probably too far to fit in with your school needs. As noted, Spurwink doesn’t have an indoor, but it’s a fantastic area to ride because it is on the beach. I’ve been happy at Hearts & Horses in Buxton since 2000 with a huge indoor. It is a casual barn, though, so you’d have to work out training needs.
There’s not much availability for eventing barns in Maine. MeCTA is the association that puts on events. I do know a couple of other boarding barns with indoors in the area, but they are family-owned and managed with limited experience caring for horses.
