This is a real simple fix, good for small fleets, and good for Cryptic.
Between each two week 200k dilithium "special time limited project," have an optional special project that gives 4000 XP in each category that is time limited to that week. The project requires 3 Fleet Ship Modules. Or 8000 for 8 FSMs. Or 20,000 for 20 FSMs. Or 40,000 XP in each category for 50 FSMs. You don't have to run any of them. You can only run ONE during the off week between the 200k dilithium special projects. The duration of the project is 36 days and it takes up a normal project slot.
Big fleets and very active fleets don't need it.
It gives small fleets a guaranteed minimum level of progression if they're willing to fork over the cash. It gives Cryptic a dead week between fleet special projects.
It's optional. You can only run ONE of them. It keeps your progression up at a pretty direct financial cost Shouldn't speed anyone up dramatically because of the time and materials involved
But if you have a fleet with 5 members and you're ambitious, you can pool your resources and drop $250 collectively once every 4 weeks to stay on track. with a 7 month finishing date.
The alternative I can see if Cryptic wants to maintain high dilithium prices is maybe giving Fleet Projects a chance to crit in exchange for optional dilithium contribution.
So, for example, every project gets an OPTIONAL 200k dilithium contribution. If the fleet receives 50k in optional contributions, they get a 10% chance to get 10% extra XP and a guaranteed 10% extra. If they receive 100k on the optional meter, it's a 20% chance to get 40% extra XP and a guaranteed 15% extra. At 150k, it's a 30% chance at 80% extra XP and guaranteed 20% extra. At 200k, it's a 40% chance at 160% extra XP and guaranteed 25% extra.
Basically, this is a crit based pot sweetening that could boost projects and is built around the idea of TRYING to get the dilithium to ZEN conversion rate to bottom out. Could be enabled for any project.
I find nothing objectionable about this idea. As an active member of a miniscule fleet myself I would never pay real money to accelerate fleet progression myself. But then again, I only see fleets as a means to obtaining a top of the line ship and with big fleets willing to sell me a days membership for 10m EC's I wouldn't need to.