I cannot believe that Starfleet cannot manage at least one starfleet ship per developed colony.
I guess we're at an impasse, then, because I cannot believe that they
can.
Edit: Not to sit there on station (whether fully idle or just on local patrol) most of the time. I do think we could manage one Starfleet hull per properly developed world, like,
total; like I said previously, my current general impression is that immediately-prewar we had less than three hundred "properly developed worlds" and a clearly-underfunded Starfleet of 150 ships; doubling that hull count is
entirely reasonable. Gluing one of those hulls to each of those worlds and then building enough
additional hulls to fulfill normal scientific, patrol, and emergency-aid duties across the
other hundreds of worlds plus exploring beyond them is
not, but that's a separate argument.
Edit2:
Also I'm pretty sure that with the number of hulls we know exist and the 800 men figure for the Excalibur, one of our largest hulls, Starfleet cant hit a half million officers and enlisted.
Oh, yeah, my wild-assed guess is on the order of 80-90,000 crew aboard ship at any given time out of a quarter-million-ish swearing the oath and wearing the uniform, and probably triple that directly employed by Starfleet but not
part of Starfleet (miscellaneous civilian contractors, sponsored researchers, the shipyard workers at Utopia Planitia, the janitors and cooks in San Francisco, the shipwrights and support crew aboard the
Pharos stations, etc., etc.) for a grand total of about a million people "on payroll" (for whatever that's worth in a society without payroll).
Edit3:
Hmm, could we possibly use surplus warp 7 reactors and single v3 nacelles for system monitors? That could cut costs down drastically.
I mean,
in principle, yes, but you're looking at "worse than a
Selachii" and expecting it to stand up to, if not invasion, at least serious incursion. That seems recklessly overoptimistic.