I know without any possible doubt that the logic train that is being followed is flawed unless there's some handwavium happening that I'm not aware of, but it's not my universe to write in. I can only do my best to point out flaws. I'm done with this topic and won't bring it up again unless the argument changes substantially.
Fine. That is your opinion, and obviously nothing I can do in the entire universe is going to change your mind. My only possible defense is that (a) I devised the technology; (b) I know the limits of the technology; (c) I know the detection limts of the systems; (d) I know the lift capability of the ships; (e) I know how much money the Admiralty has to play with, how much manpower it has, and what its strategic priorities are; (f) I've studied military and naval history for the last 45 years; and (g) I am concerned about the navy's ability to do its primary job -- which is fighting an expletive-deleted war for survival while striking an effective balance between combat power and sensor capability.
I could continue to discuss your responses on a point-by-point bais, but since you are now (apparently) positing a sufficiently inexhaustible supply of enemy starships to do unlimited in-and-outs which, obviously the Manties are going to be too stupid to recognize and do a single expletive-deleted thing to cope with, there doesn't seem to be much point.
However,let me try this one last time.
(1) The Manties have a finite supply of money, manpower, and logistics.
(2) The Manties are not and never have been interested in building single-purpose ships which are incapable of contributing to their net combat power unless it is the only possible way to get that single capability.
(3) The RMN is fully capable of performing the mission you are describing using ships which are also combat-effective and is not interested in deliberately building death traps/noncombatants simply to guarantee that no one can possibly use the ships for some other useful function.
(4) The smaller the ship the less capable it becomes, not simply in combat but also in other venues, including its inability to carry worthwhile numbers of the remote and unmanned (and hence expendable) platforms which will do the actual scouting in the high-risk zone.
(5) Ergo, with all due respect for your belief that the Admiralty must be staffed by idiots if they choose not to pursue your forward-looking, insightful policy, they are not interested in buying any significant number (defined, in this instance, as more than one) of vessels which are unarmed resource and manpower sinks for the sole purpose of performing a mission they already can and (and already are) performing.
I will add only that I resent (a) being informed that I obviously do not understand my own technology (this from someone who seems to believe that frgiates can go higher in the hyper bands than anyone else) and (b) being informed that I am resorting to "handwavium" when I have given specific supporting logic for each of the points I have made. I appreciate the interest in the books and the technology. I welcome questions and debate and, yes, on at least two occasions I can think of I have picked up on logical implications of my own tech which had not occured to me before the discussion. This is not one of those instances. Before you lecture me on the best mix for the RMN in light of its fiscal and manpower restraints and the nature of the mission it actually faces,it would be a good dea for you to know what those limitations and that mission actually are.