Correct on the rental, also the insurance is expensive but worth it depending the location and traffic in the area. Renting the trailer is the lowest cost because they have not been charging milage or Gas refills.
two over head are because of either using stereo sound ? or area of coverage and with the area of coverage you need to have the 3 to 1 on the top but also have equal distance to the snare. If the two are not the same distance from the snare there will be phase problems with the snare bleeding into these two mic's.
I will use a single 9 out of 10 on overheads.