I'm not convinced that the spare does not restrict too much air flow to the radiators. I lost a fan clutch on my Ford and was able drive the length of South Dakota (Rapid City to Sioux Falls) during the summer without it although I was loaded over 19K lbs GCW. I don't think I would have been able to keep fluid temperatures low enough with something like that in the way.
In Sioux Falls, I had a clutch waiting for me and was able to continue on the next day with full cooling capacity and only losing about half a day in the entire process.