Maurice,
Check this beast out...
http://www.theelectroniccompany.com/detail.aspx?ID=35
It would probably work, but is brute-force...
Can you imagine this beast attached to Mr. Buzzy, an old univolt?
hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm
Tranformers do not provide any isolation or noise immunity, but then again these are campgrounds -- they are probably as bad electrically as they are here...and univolts seem to be tough...
Tell me what you think before I go over and try to help...
Rob