Strict neutrality is a hard row to hoe. I did something similar with Belgium, but they have a lot more capacity to field a deterrent army. (And slightly more ability to produce goods for basic internal needs.) Of course, with just one province to worry about, I'm sure you can reap great dividends from forting up hard and maintaining a highly survivable premium army (perhaps guards/artillery/cuirassiers). If it becomes an issue, the Chemistry techs can really help chokepoint defense by increasing supply limits (and the population growth can't hurt).
On the domestic side, your international market needs are going to be harsh. Sphere markets are one of the aspects of the game I am still struggling to fully understand, but getting into a sphere might not be a bad thing if it gives you any kind of access priority to vital colonial goods like fruit, tea, fruit, coffee, fruit, tobacco, fruit, fruit, and fruit.
Good luck.
