With these DPFs, I would run the engine fast and hot. Running these engines at lower RPM could cause more buildup in the DPF. Unless your tractor doesnt have a DPF, then probably 15-22rpm would be fine. For me, I crank 'er up get it done. Not all the way, I am not wide open, but right around the PTO rpm.
PTO or slightly higher. Gets it done faster, keeps the regen down.