One rule of thumb I have found from looking at both US and UK force constructs for the Army in that there is generally a 35-36% of the force in Combat Units.
46-47% in Support Units - and the remaining ~2% in overhead (admin units)
No granted down here we do put more Support in the Reserve (not ARNG, but USAR)
Down here we are pretty transparent - so for your reading pleasure (has nice graphics too)...
Plus this lovely little tidbit on P.29:
However, DoD currently describes scenarios involving Russia and China as its most challenging potential con- flicts, and the particular strengths of Stryker BCTs would not be especially useful in those scenarios. Armored BCTs would probably be preferred for responding to Russian aggression against the Baltic states, and infantry BCTs would probably be preferred for responding to Chinese military action against Taiwan or other states on the South China Sea.
Also what I found relevant to Canada is the "Special Topic" on P.38
Integration of the Army’s Active and Reserve Components
In short given the size of the CA, I think the 4 Regular Bde (3 "CMBG" and 1 CSSB) is a little overly ambitious, without PRes integration - given the Support needs of an Expeditionary Army...
If the PRes can be effectively leveraged - then I think that the CA could actually field two functioning DIV.
BUT that would require massive capital investiture - something I strongly doubt that the GoC would support.