To answer a few more of your questions The motor temp never gets over 135f and the ESC reached a peak temp of 98.9f.
The Castle 160HVf comes with a fan attached that I connected to Receiver power and seems to be really efficient at controlling ESC temps. I have recorded a 119f ESC temp on one flight on a warm day. The above pictures show the new Vario Prop on the left with the spinner I modified to fit the Zinger four blade which needs large blade cutouts. I already have a new Dave Brown spinner cut for the Varioprop, it has much smaller blade cutouts. With the special prop cut and 10mmx1.25 XXL Vortech nut the cost was close to $90.
In the right picture the funny looking metal duct picks up some air from the chin scoop in the P 51 engine cowl and delivers it to the stagnant area at the top rear of the Rimfire motor. Cooling air flow has to enter from the front, turn 180 degrees, go through the motor back to front, then hit the spinner back plate and turn 180 again to exit through a large hole in the firewall and flow through the fuse to exit the belly scoop exhaust and the tail wheel opening. Motor temps without this duct reached 200f +. After I had the idea to try this dumb looking thing motor temps dropped to 160f. I then shimmed the RimFire motor forward to increase spinner back plate clearance to 1/4 inch. This last mod lowered motor temps to 135f. The duct used is auto heat riser duct from Advance Auto Parts. It is cheap and the cooling effect is very effective even at low speeds and taxiing. I shaped it with my fingers and a round piece of wood and used Gorilla glue to secure the duct to a couple of u-shaped balsa blocks. some of the air is bypassed to cool the ESC which I later mounted to an airply plate below and behind the air duct. Going to the Castle 160HVF from the 120HV meant making a dent in the rear of the duct for ESC clearance but no problems with higher Temps. One last detail is the lower belly sheeting is removed in the picture to cut an exhaust ramp in the firewall for the ESC air. If you look at the belly in the left picture you can see this exhaust port, lined with aluminum duct tape it is almost unnoticeable. I started cutting this exhaust port several p 51s back for muffler cooling and it is effective for that also. The left over tank vent is still in it as is the anti-spark switch for motor battery arming. When I run this plane with a DA 50R I just add the fuel dot to a hole next to the tank vent. These parts are not visible in flight.