I just spent a day using a ride-on vibratory roller with articulated steering, and it's a different beast handling wise. Have you ever driven anything using articulated steering?
I see you have the frame started according to your post. Can you modify it to a more conventional steering setup if the articulation doesn't handle to your needs?
I have been on machine that uses articulated steering, and you're right, it is definitely different. But the whole machine is designed around the articulating joint. I like it, because it is very simple. This is not going to be a high-speed machine anyway. It's going to top out at about 20 mi./h