TLR! Nice!
Get down low for sure! I almost always do that. Not always to this extreme though:
Triple Barrel by
Gilbert Kless, on Flickr
I hate when people get pissy too. The one time I remember getting like actually annoyed was for this shot:
F40 by
Gilbert Kless, on Flickr
That thing rolled up, and naturally that entire car show of about 250 people flocked there. I waited in that spot for like 15-20 minutes, crouched down there. I remember getting annoyed, not verbally but the look on my face probably said enough. I finally had enough, grabbed a shot or two when there was finally enough of a clearing, and then just saying screw it. I didn't get what I wanted, had to crop all weird and the space on the left really bothers me, but I had to get something of that car with that license plate. Afterwards I thought about it and figured out I should have just come back like 10 minutes later.
But for the most part, people are like you described, they move out of your way. Most car owners will go out of their way to help you get the shot too.