Chris,
Sorry our whole crew couldn't make it. Would have been nice to meet you.
The Road America event was a 'low key' vintage event. There was a MUCH larger one farther east at Watkins Glen, which attracts the fast cars and really cool cars. There are about 3-4 events like the Watkins Glen event in the country every year. The VSCDA Road America event is a typical 'regular' vintage meeting. Vintage racing is currently fragmented in the US and there are multiple events scheduled on the same dates, so car turnouts tend to be less than they would otherwise.
For reference, the fastest 4cyl cars (MGBs, TR4s, Spitfires, 356s) turn times in the 2:45-2:43 range at Road America. Pat Ryan who was racing a Trans Am Camaro that weekend turns 2:43s in this car:
https://britishracecar.com/PatRyan-Triumph-Spitfire.htm .
The tires used in vintage racing in the US aren't real conducive to rain racing, which means buying a different set (plus wheels). Most racers just don't bother with the expense as it doesn't rain too often, at least compared to parts of Western Europe. Road America does seem to be an exception though, as many of the SCCA racers can attest to.
Glad you enjoyed your time here.