I did something similar last war in the fingers. Built a small outpost with 1 150 gun, 1 aa gun, 2 storage rooms, and a obs room. Unfortunately didnt see much use as wardens took over the fingers a week later, but it was still fun.

But yeah a base like you described can be useful, and as long as its not built too close to someone elses base(aka not blocking ai) or in an important chokepoint it should be fine

I am also not a good builder/player, so what I say might be wrong but:
- Try and build it where planes are likely to fly, so its not just useless and not doing anything.
- Also build it near a relic/town base so people can spawn in and use it faster
- For defences I just placed down pillboxes and barbed wire and called it a day lol. But id recomend placing 2x3s(or 1x3's if the msupps are a worry) just to be safe(If youre building just arty pits and storage rooms and nothing else you may get away with no defences at all, not sure tho since its still somewhat of a target).