present logbook is OK. if you mod the car extensively and want to reissue the logbook, take it up with tech and see what's involved.
mustang is definitely limited in options. STL has so much crossover from ITA, S, and SM that I'd choose prod like you originally suggested. are you Mike Horn?
as an aside - I don't know if they will be implementing the qualifying rules about being within some percentage of the pole, but if they do, ideas like this will be affected negatively. them might just do it for big fields, probably SRF, SM, STU and L.