Since cops offered to come by ask them politely if they can:
a) give you one of their portable radios (slim chance but worth trying)
b) give you number of somebody who is going to be patroling the area
c) give you direct number to the station

That way you can shorten the response time by a lot.

Something else that I've seen cops doing a lot during comfortations is using open chanel. Obviously your radio communication is not being recorded so having open transmition won't help you much but if you have a small tape recorder it may be a a good help in case person you cought denies stuff later on. Also if threats are made to you it's hard to prove it in court since only two of you were present at the scene. Having a tape can make a big difference.

Matt