I need a remote shutter release for Mamiya RB-SD. Of course, RB uses threaded type release so any kind will do but I have one requirement. It needs to work from at minimum 30 feet away, hopefully 40 feet. Looking everywhere, I can only find the bulb type release.

Are there any OTHER choice? I would really love to have radio control type but I cannot find one with mechanically actuated threaded adapter. I can DIY but I'd like to avoid that if possible.

It does NOT need to be the double kind. I'll just raise the mirror manually and trip the shutter only via remote.