Sorry for being a necromancer, but, I've already asked if it was OK to throw in my two cents anyway.
So the future of clan bases is on the line, then what's the facts? Facts are... Population is low, and running a server ain't free. It is clear that clan bases doesn't cut it anymore as there aren't enough people make clan bases a sustainable source of income, yet they don't actually cause any problems still being there that I'm aware of. There's probably somewhere close to a 150 systems to pick from where 10 of them is occupied or "held" supposedly in case of any veterans returning. To me, it's very noble of OP to keep a few pieces of history intact, even if nobody can access those bases. It gives me a peak into the past of how big this mod was, which is incredible.
I don't see a reason to change how clan bases work or how much they're paid for... Maybe, considering the population it'd be a welcoming change to lower the amount of resources it takes to build a base but that would probably be more work than it's worth. If you think about it though, back then there were probably 10 people shipping goods compared to today where one is lucky if there's 3 people shipping goods to construct the various modules.
What about a different source of income?
I think personal bases is the future. The foundation is already there with the clan bases, now just make 'em, smaller, cheaper, not as powerful... I haven't done any deep-dives into the other mods such as Discovery but I've tried it, and I remember they had personal bases in there - I just don't know to what extent they serve, but they've got the idea anyway. And I think the "admin station" sort of work they way I'm trying to picture here but I don't think I ever tried to launch one during my time as a GR.
A funny coincidence too, there's another game I usually return to on a regular basis, one that I have referenced almost as much as I've played it, Planetside-2.
While its main gameplay-loop is to shoot some noobs and take over continents by converting pieces of the interactive world-map, there is an entire gameplay-loop dedicated for those who doesn't enjoy the chaotic battlefields... Base building. You can spend hours just building a base and collect materials to construct new parts of the base, very much like how our Clan Bases work, except they're designed to be run by 1-2 people and they aren't permanent. The personal bases in Planetside-2 is modular too, which means you can help expand another players base to fortify its defenses, create more spawn points, construct vehicles or long-range weapons like orbital strikes. Some of the craziest bases I've ever seen in that game were run by an entire platoon (aprox 40 players) who kept expanding upon one players base.
Problem with this idea is of course that people could view this as pay-2-win depending on how the payment is laid out. But, I would personally be happy to contribute and pay to deploy a mobile spawnpoint knowing the money goes into even more development and server upkeep fees.
But why on earth would someone pay for bases in Crossfire when there's other mods which lets you build bases for free? Well that's where Crossfire's bases need to be different, and worth a few bucks.
And also, somewhat related to this... I would like to suggest OP to add an international payment service such as Payop, I know other private servers for games like WoW and Aion uses it and/or similar services, which makes paying a lot easier than having to deal with IBAN numbers. This payment service also have quiet a fitting name, doesn't it? PayOP