Makes a lot of sense Paul and I feel a lot of that past Earth precedent implies it could easily translate to Star Wars overall too.†
It's a similar thing to "loyalists" in America's infancy conflict, where whole regiments were formed of loyalist volunteers who weren't accepted in the British regular army but who fell under British military control/commanders.
I think on Rodia (just as an example here) we'd have a planetary governor...† An elected official, a figurehead, who reports to sector leaders or Moffs/Grand Moffs...† Under the governor there are two possibilities then though.† A planetary homeguard which is integrated and basically controlled by the Empire...† The degree of control depends on the degree of the planet's overall assimilation into the "New Order".† Do they willingly (the majority of course) want to be part of the Empire?† Do they have a budding civil war on their hands over the issue?† Do they have minor insurrection?† Do they have full support even perhaps for the New Order?
If the planet's in pure turmoil then, the other possibility is that there's perhaps still homeguard units, but the overwhelming military presence is going to be Imperial, even if it's not the majority...† It's kind of like the military presence in Vietnam which escalated from simply advisors to full blown US military running of the show over there.†
So like on Kashyyyk, a military presence of Imperial regulars, stormtroopers, or a mix of troops/military units is there because the (EU) situation on Kashyyyk is volatile...† Wookiee's are a subjucated species overall, or so the writings go...† With prisoners being put into slavery and whatnot.† Obviously there's probably gonna be less of a "homeguard' for Kashyyyk then there will be for other planets then...
There's a lot to think of with all the different species...† It'd be really cool seeing what they'd look like too.
Like for instance, could you picture the Imperial Army Regular uniform (AT-ST Driver) on a Rodian?† The green hands and things.† Maybe a special patch on the shoulders (perhaps below the Imperial logo) for the Rodian Homeguard.
Needless to say I have a custom in my head here, haha.†