Mark,
You have discovered the joy of owning a different car rather than following the rest of the crowd. You're car is cute except I don't think it would be big enough for my body:-) But what fun you must have as you cruise into a show with something totally different.
A lot of the concours crowd as you have found are fine and not uptight. Careful how you use the word "classic" as you may get the CCCA "classic" police after you. Classics as define by them and also the Concours are a limited amount of fine cars made between 1925 and and 1948. There is a list of them on the CCCA website. I won't bore you with the full definition. There were actually were very few classics at the show vs. the amount of total cars. However I do understand that a lot of people use classic for cars that they consider old which is OK by me.
You need to take your car to the Lake Oswego car show Aug 24. That has a lot of unusual cars that come out of the Lake Oswego garages. A lot of foreign flair so you should fit in.
Oswego Heritage Council - Car Show