I think you're thinking too hard. It's just for fun, I don't think you need hard evidence of someone's victory.
The rally should focus on one plane. Each one has it's own strengths and any given race type has it's ideal plane. A2A does not have dozens of similar planes like other companies do. If it's a long distance run, just load up the B377 with it's 47,000 lbs of fuel...
If you want a P-51 course, then it should focus on it's high speed, long distance qualities. Further, I think the course should have fuel stop strategy in it. I mean, otherwise you'll just be buzzing your engine along, accusim or not.
All my ideas have the same ground rules. VFR flight. Use real-world weather. I understand that this doesn't make the simulation 100% fair but who cares, no weather is boring and same weather for 1000's of nm is boring too.
There's "checkpoint" airports which must be landed at to count. This is as simple as one wheel down. ATC should be followed as applies to VFR. Getting between checkpoint airports should be done via airways or other standard navigation. My routes involve radio navigation so the pilot has something to do on the flight. Actual routing is up to the pilot which is where a lot of strategy comes in.
If you need to do anything to your plane, such as refuel, you must land at an airport (any airport is fine) and taxi to the fuel pump or where ever might be appropriate for the P-51, such as in front of the terminal at a small airport.
Having anything done to the plane during a pit stop carries a time penalty. All pit stops must be at least 60 minutes long. Here's some examples I came up with:
Others 10m each
Maintenance hanger window 0m
Engine window 0m
Compression test 1h
Filters 1h each
(Oil, fuel, air)
Minor 2h each
(pumps, generator, starter, magnetos, ect)
Major External 4h each
(supercharger, landing gear, ect)
Major Internal 8h each
(Main bearings, cylinders, ect)
There's two time-saving options I thought of for your pit stops, the quick fuel option, and the engine rebuild option.
Quick fuel: If you waive the ability to check the maintenance hangar and associated windows during this pit stop, then this pit stop does not have a minimum time. In other words, you could park, fuel, take your 30m penalty, and then take off again if you don't inspect anything on the plane.
Engine Rebuild: If you have to replace the main bearings or a cylinder (for the cost of 8h) you can repair anything else you want to at 1/4 the time cost. So if you take 8h to replace the main bearings, you can replace your supercharger for 1h, and your starter for 30m, for a total repair time of 9h30m.
Anyway. that's it for the rules. Pretty simple. Your routes need to take into consideration airways and fuel economy. Where should you stop, and when? How fast to fly? Fuel up at a checkpoint runway or this little airstrip that's on the way?
I can think of three rally types.
-Minor fuel planning
Minor fuel planning would be over a relatively populated land mass where your actual plan of fuel use is relatively unimportant because when you run low you can stop just about anywhere and load up some more. Focus here would be fast running and repeated fuel stops.
I have a sample flight plan that follows the two extreme corners of the United States, stopping at interesting places along the way approx 200-400nm between. It starts at PADU (Dutch Harbor, AK) and ends at KEYW (Key West, FL.)
-Major fuel planning
Major fuel planning would be island hopping or the equivalent, over vast expanses of area with very little in terms of airports. Here the checkpoints are up to 1000nm between (although I try to keep them 200-400) and as a result fuel planning is very important because you'll drop into the ocean if you don't dial back to cruise power settings.
I tried to keep things interesting with my sample flight island hops from the remote NTGJ (Totegegie Island in French Polynesia) all the way to RJTT (Tokyo, Japan.)
More of a "game" style. Where the other ideas for rally is "who gets there first," this idea has a race in a certain area, with area airports have assigned point values to them, with pilots given a set amount of time (say 12hr) to land at as many airports as they can in the time alloted and get the most points.
Pilots can start at any airport with points, but they don't get the points for that airport. Fuel stops and repair time penalties works as it does in the other rally types.
This works best with a relatively small area but not too small that it's just a bunch of take offs and landings. I thought the UK and Ireland would make a good spot for this.
The race would occur at a set time and the players would set the game time for this and not change it till the destination, except adding time as needed for pit stops so you don't have to sit idle at your computer. For people who have weather programs that set weather to historical records would be ideal to make it fun but justing present weather through FSX would work too.