If the computer racing software could do races within races multi class heats could work as long as the classes have a similar speed (like F1 an LM cars).
Im sure that classes like VTA and USGTwill have enough cars to have their own heats an Main . If you have only 3 F1s an 2 LM cars that could be combined. Ive seen other classes of cars that could work well toghether Euro ,mini, TT01 TT02 classes (only if needed to be combined)
Some things that will not work a new person with a silver can TT01 with Open Touring speed difference are just too much.
If the masses of racers this year are much more then last , I know that St Charles does 2 5min qualifiers an 5 min main you could reduce it to 2- 4min qualifiers and a 6 min main and NO time between Quals an Mains (except time to resort ect.)It woul be nice to see a difference bettween Qualifiers an Mains
If there are enough new onroad car racers it would be nice to have a onroad Novice/Sportsman class . There is nothing worse that hitting a newbies car because you have NO way to avoid it (Im sure they Dont like it either , an they could be move up when they are comfortable)