Well, achieving the 100%'ish isn't a problem with COH2...
temporarily.
The benchmark:

Yay, 100%'ish load.
But an actual game:

23 minute game, Rzhev Winter, 3v3,
medium settings with AA & vsync off
Started out with fluent 80-100 FPS, went to crap a little later. Probably would go down further over time.

30 minute game, City 17, 3v3,
low settings with AA & vsync off
Same again, decent load at start, all fluent, and then drops FPS & load after a while.
Funny detail: GPU clocks down due boredom.
...
My conclusion from this is and the fact that my load was not at 100% in the 1080p test, is that my GTX 970 is not the limiting factor in 1080p....
I can then assume the limiting factor for me is the performance of my CPU (now rather old i7 3770k even with a 130% OC), and more precisely its limit on a single core (because the game is not well enough multi-thread optimized).
Most likely. My CPU seems to be around 30% load all game long.
But let's be fair here for a second:
http://www.cpu-world.com/benchmarks/desktop_CPUs_single.html
https://www.cpubenchmark.net/singleThread.html
... and so on.
Your CPU in this regard is still pretty much as good as they get. My little Xeon doesn't have to hide either. So what kind of CPU setup do we have to own to keep up?
hmm... someone got a heavily OC'd nitrogen cooled dual core around?
Nevertheless, the performance degradation is rather severe in this game, and sadly unavoidable atm.
- my 2 cents
Apropo, to answer the original question from OP:
you want more GPU load? Ramp up ze graphics. Will at least give you some load at start.