.... Could a people-mover and a park & ride for the summer months break even? ....
One of the First Great Western regional managers explained to me once that even a pack 2 coach train running up and down a branch all day would not break even, although it's possible to do very well, thank you, on a 125 operation. Reasons included things like:
Lower pence per mile fares on the branch
Fewer miles per hour on the branch
A longer proportion of time spend loading / unloading / turning around
Fewer passengers per crew member
More fuel needed per passenger on the shorter train
More stations served in a given time, so relatively more Network Rail station charges
Shorter distance traffic tend to be more peak-time biased
That's not a full answer to the question, but gives you a flavour of just how uneven the playing field would be for you.