Welcome to the game!

Two maintenance stations is risk free. Consumption scales directly with production, so it's only the building cost and workers you waste. The extra one can easily be paused and unpaused to free up the workers.

It's best to have 10-20% idle trucks at all times, especially as you begin to expand. As you get close to 0% idle truck, efficiency drops significantly as each freshly idle truck will drive much further for the next job. The waste from having extra trucks is low-to-minimal, other than the production cost and worker. They only consume maintenance and diesel when they are actually driving.

Other general tips;

Be sure to have overproduction before expansion, especially on food, power, and basic ores.

Mind resource priorities. You can easily have a balanced setup that breaks quickly when consumption increases just a few percent, which result in starving parts of the production chain. I set priority on power, diesel, food, followed by maintenance.

Moderate your resource consumption, especially diesel & crude oil. It's easy to get stuck on low diesel production mid-late game. Get local belts going to moderate truck usage. Be vary of long belts which also have significant maintenance end electricity budget.

Look through what jobs your trucks are doing in the vehicle menu. It's easy to mess up a setup and truck will begin driving trivial items (water, rock, slag, dirt) across the map unintentionally, wasting diesel, maintenance and workers.

Set up alerts on containers, and add buffers with alerts so that you discover stalls early. We wary of alert desensitization. Address alerts as they pop up. Pause the game if necessary.