Which route are you taking? I don't remember much in the way of hills when going on the blue option.

Have done it often.

Maryborough to Goomeri then through Nanango to Yarraman. Turn right to Cooyar and then on to Crows Nest and Toowoomba.

There is a short cut from Tiaro to Kilkivan through Gundiah but it has a couple of bits with no line markings, so if not comfortable with that go down the highway and turn onto the Wide Bay Highway near Bauple.

As with all Qld "highways" it can get a bit bumpy in some spots but mostly smooth sailing.

If wanting to bypass Toowoomba then go via Oakey as above.