I really don't want to get into ships being on planetary surfaces due to the complexities involved with landing/taking off and atmospheric effects. Keeping them in LEO is a lot easier. The idea of maintenance facilities, like shipyards, being in orbit is probably the easiest option. The only downside is that at the moment you can put maintenance modules into PDCs so that would have to end. Perhaps the easiest thing all round is to remove the existing ground-based maintenace facilities entrely, remove the option of PDC-based maintenance modules, extend overhaul ability to ship-based maintenance modules and make maintenance modules a commercial system. This means all maintenance modules are orbital and are built by commercial shipyards, either within bases or ships. It means I can remove code rather than figuring out new code and it also means I don't have to create a new type of object and therefore a new type of contact.
Hmmmm - I think I'd prefer status quo over this. The main issue I have is that it makes constructing and tracking maintenance facilities (I fear) MUCH more difficult (read micromanagement) than the current situation, and the evolution of the game seems to have been away from maintenance complexity. If it's the case that it's too much coding in order to make a "maintenance yard" flavor of SY, then I think it's better to leave the current system alone and account for orbital infrastructure and shuttles as part of the maintenance facilities.
The caveat to this would be if you introduced major space-station construction rules (i.e. that were built by industrial capacity rather than SY and class designs). If that were the case, then I would argue that "maintenance bays" should be a system that could be added to a SS, and that each bay could support e.g. 5x its hull capacity (e.g. a 5,000-ton bay could support a total of 25,000 tons of ships at any one time (the 5x represents them cycling through) and one ship in overhaul, with no ship being more the 5,000 tons).
More free-association here: what's the difference between a hangar and a maintenance bay? It seems like the main thing is that hangars allow a quicker launch. This is reminiscent of the two types of troop transport bays. That being said, I think anything that's done to change the maintenance rules should keep them as simple as they are now, without the need for detailed tracking....
Removing the ability of maintenance facilities to re-arm box launchers is easy enough, although bear in mind you will need some very large hangar bays if you want to be able to re-arm the box launchers of larger ships. The Soviets in my game have 30,000 ton ships with box launchers.
Hello, Law of Unintended Consequences
What I was intending to suggest is that one shouldn't be able to base 100 "operational" fighters on a planet with 2-3 maintenance facilities and no hangars. To put it a different way, I think that operational fighters should be required to base off of either a ground-based or ship-based hangar. This is a different situation from large ships, because they'll have their own life support. I can go either way with GB, although it's probably easier to consider them ships. So this was actually intended as a basing requirement, rather than a reload requirement....
John