The ALICE gear from the 80’s/early 90’s had a designated pouch near the buckle of the pistol belt for holding a field dressing. But you could attach extra pouches to the belt, provided you could get your hands on extra pouches. ALICE was much easier to modify and add to than the British load-carrying equipment of WWII.
Well, unless something goes terribly wrong during a re-enactment, I think those dressings should last you for a lifetime. 
As for field dressings under scrim nets on helmets, the Canadians seemed to do it.
When it became apparent that the First Field Dressing carried in the right-thigh pocket of the Battledress trousers was inadequate, a large Shell Dressing came into use by combat troops. This bandage was too large for the trousers’ pocket and was carried under, or attached to, the helmet net. In that position, it offered the additional advantage of breaking up the helmet’s distinctive profile.
http://perthregiment.org/rperth4.html
And see the many photos in the link of dressings under helmet scrim nets.
P.S.
Note that a FFD and a Shell Dressing are quite different things and quite different sizes.