There's some stuff here that might be applicable, don't remember anymore what maps i put into this zip. (2.4 megs)
Off The Top Of My Head
or now that MPQ is back you can always go there and browse ^__^
...you've had a look at qtdm1. Would it suit for this sort of thing? As with qtdm3, pre-release for a specific purpose wouldn't be a problem.
Woop I Got Props
I'd vote damaul7 but that might take a long time on the last 2 players as it IS pretty huge.
get PROX mod - it has some maps for CA gameplay (just check which, some are 1-1 RA trype)
If I recall correctly, everyone except for Speedy made a CA style level in their multiarena map. :D