I think you should get real ski boots or roller ski boots with a proper ski binding. I recommend combi boots.
Ah, this is another story, and a good one.
I initially bought the whole package: real ski boots + bindings, in an attempt to feel like a *real (roller) skier*
For the following year I suffered: discomfort, aching feet, bad blisters etc.
Still, I soldiered on trying to convince myself that it will get better with time.
Finally, on June 6th my Rotofella bindings failed catastrophically. The little internal metal tongue that engages the metal bar at the tip of the boots broke in half - metal fatigue I assume, because there is no direct 'user interaction' with it.
I fell badly, bruised my ribs in the process and was out of commission for 2 weeks.
Next, I took a pair of old running shoes and screwed them directly to the top of the rollerski - with do in in rowing shells all the time.
You are smiling with disbelief now, but that actually worked 100%.
Perfect comfort, and control even better than with the dedicated ski boots.
I picked shoes with very thin sole, that raised my center of gravity less than the combined height of bindings+ ski boots, and that in turn made the whole setup more stable, especially on uneven surface.
I assume this would not work with skating technique, but for the type of rollersking I do (flat, straight trail) it worked perfectly.
The problem? It started raining here in Oregon. I had to either put on the rollerskis next to my car, or walk (barefoot) to the trail.
My socks were getting wet, so on to another solution.
I pilfered some old snowshoes, and after some hacking adopted their bindings to the rollerskis.
It works somewhere in between : not as good as the sneaker-to-ski direct, not as badly as the ski boots+bindings.
I will keep on using them for some time, and then decide what's next.