A bit of an anecdote regarding the timing trailer, and particularly the sign.
BMC did a lot of record setting on the salt during the 1950s, and they used the same timing trailer over the years, but if you note the sign, at 3:44 . . .
https://www.youtube.com/watch?v=o2KuaKt2uDgIt has the AAA logo on it.
At 9:04 in Sid's video, you see the same trailer with the same sign, but the AAA painted over.
This was after LeMans in '55, and after Triple A got out of sanctioning events.
But yes, a 10 mile circle, capable of operating under 24 hours of use.
Sid, I'd love to see some pictures of that equipment.