Your best bet would be a station with a recreation module that serve as a means for resting your crews, you then add some maintenance modules to it to serve whatever ships you need docking there for maintenance. The recreation module is 100.000t and each maintenance module is 5000t and service 200t of regular ship. So a station that is 360.000t would be able to service about 10.000t of ship.
You will have to station it at a planet, moon or asteroid to use it though so you can then ship fuel, minerals and supplies to that body and role-play that it is actually on the station.
Although, you probably would need a large empire to find them useful or in case you want to build up a forward base quickly someplace.
Here is an example base...
Nova class Maintenance Base 358,350 tons 3590 Crew 13665 BP TCS 7167 TH 0 EM 0
1 km/s Armour 1-449 Shields 0-0 Sensors 1/1/0/0 Damage Control Rating 17 PPV 0
MSP 405 Max Repair 200 MSP
Intended Deployment Time: 3 months Spare Berths 1
Recreational Facilities
Maintenance Modules: 50 module(s) capable of supporting ships of 10000 tons
This design is classed as a Commercial Vessel for maintenance purposes
It is not cheap but also not that expensive for how mobile and useful it actually can be. Just building the maintenance facilities in a planet would cost you 7500 BP so its just twice as expensive and that is not counting everything else you will need to do with a real colony.