Plenty Highway

Plenty Highway can be pretty rough , especially on the QLD side. Wouldn't expect to average much more than 70 kph.
You may be lucky and travel just after a grader has been working.
Cheers
Jim

Tobemorey to Jervois Roadhouse:
Distance: Approximately 520 kilometers
Estimated travel time: 6-7 hours, depending on driving conditions and breaks
Road conditions: The road is mostly sealed, with some unsealed sections. It's generally in good block blast condition, but can be affected by weather conditions.
Happy travels!

In my opinion you won't be missing anything if you pushed through to gemtree.
We found Jervious run down and no care given. Things might have changed since we wrre there just before the rock climb was closed.
Tobermorey was newly reopened to campers after the floods so that was a bit of an ordinary experience too.
Gemtree on the other hand was outstanding, glad we spent a few nights there.
On the way home used the sandover highway, camping almost non-existent but its there if you look hard enough but free camping would be hard for vans. They have very little traffic so the road conditions are generally far better than the plenty.

We travelled this route in July 2021, so a while ago. I expect travel time will vary with conditions. There was a section with lots of deep bulldust patches spanning the width of the road and a kilometre or more long. Corrugations weren't anything out of the ordinary. Note at that time Jervois was closed for fuel on Sundays with a surcharge to open the bowser.