But when it comes to CSS* it's a complete disaster. Despite the best efforts of some very dedicated and motivated pers. And half of that is that the systems in place don't jive with ARes routine. They were established only thinking about Reg Force Svc Bn and 3rd line and back support construct.
I really can't understand why CSS should be hard for reservists, and, if I'm reading you right its the system itself that does that.
I can't think of anything easier to form and run than a PRes transport company. It's one of those things which we need only in a limited way as a full-time resource in peacetime but you'll simply never have too many of on operations. We could form independent transport companies that could be located anywhere in the country and slotted in pretty much at any echelon level on deployment.
Supply is the same. Additional people, trained in running the supply system shouldn't be hard to train and sustain as reservists in even the most austere armouries in peacetime to bulk out the system in a crisis.
Maintenance is a challenge but training reserve maintainers and keeping up their military skills is doable.
Where the system falls down is expecting part-time truckers, sup techs and especially maint techs to actually do the job part-time during peacetime. It can't be done. Delivery of CSS services in peacetime, regardless of whether to a RegF organization or a ResF one is a job for full-timers and not part-timers. CSS reservists, OTOH, are invaluable in an operational surge roll and should be organized and trained for that.
I'm not sure what role a ResF Svc Bn has under our current construct. To provide CSS for a non deployable, non operational CBG? Surely not! That only leaves an administrative aggregation role of CSS elements in a given geographic region. I expect that ResF Svc Bn headquarters are as efficient in learning and practicing their operational jobs as ResF armoured, artillery regiments and infantry battalion headquarters are at theirs - in other words not at all. So I do not see a ResF Svc Bn with any realistic role in preparing a bn headquarters and its elements for mobilization as a bn any more than we expect the QOR to mobilize an infantry battalion headquarters and companies under the current construct.
We literally have a division's worth of reservists. The fact that they are hard pressed to do a company level exercise much less a battalion one is a scandal over which heads should have been rolling continuously over the last half century.