I thought about adding a hangar or two to the design, and base scouting vessels on board. That way, the expensive sensors don't cost maintenance. And the above design, just under 20% of the cost is fire controls. Adding hangars would allow for more fire controls while keeping that ratio, allowing it to be easier to upgrade fire controls.
But giving the base even a little more crew endurance is surprisingly expensive. A lot of the hidden cost of base tech railguns is the crew requirement. Going from .1 to 1 month endurance adds over 100 BP on a 300 BP design.