There are plenty of gas rules at many shows. Every show is different and that must be investigated before you go to a show so to follow the rules. I always thought that in the beginning of 1972 in the rule book that is says you must use a stock tank. This was used in the car I work on a 1972 Pro Stock Cuda, Still use the stock tank that has a drain plug and that plug was installed because the gas failed at an NHRA meet coming from Canada to the USA. Now what would of happened if the person that got touched decided he was assaulted and took thing in his own hands and things got out of control. Some times it is better to just walk away as was done. Unloading for these shows is always a Shtshow and stressful. Chicago seems to always toss Winter Weather in the mix for the fun of trailering you car to the show on this weekend.
As for Canadians many did not even look into bringing their cars to the show. There are 7 1971 Hemi E Bodies within 10 miles of each other just east of Toronto but the board was not open to bringing them till less than a week before the show, .The Canadian Government still wanted a Neg. test to come back into Canada even after they did open the boarder up for travel to the USA and that test is a pain in the butt to find a place to get it and is far from free. So the 1971 year was missed by the Canadian cars that is to bad but it is only a show and maybe next year some will take a car or two.