Hmm 15 teams is just too much. There'll be teams who'd be ignored totally in the edit (just like how the 20 players seasons of Survivors are) I think 12 is a great number to start with.
If they are all former racers.........we already know who they are.......right? What's the use of spending screentime on the losers?
If you watch a NASCAR race.....do you spend time looking at who is at the tail end?
?
If you watch the Kentucky Derby, do you watch the horses at the back of the pack?
By the way Danooky, you almost figured it out. You do have to think a bit. You could do the same thing with 13 Episodes and 16 Teams....
I do mean a standard Finale with only 3 teams.
The only limiting factor I could see, does WRP have enough soundman/cameraman crews to follow that many teams.