The V Force problem was Noforn and UK Eyes.
I can't talk of the 70s, but in the 60s there was a nav rad at Lindholme, George Chabeau, a very intense instructor who taught the black science of servos and transmitters.
At 1 Gp the Ops 2 position was a USAF billet and he would cover for Ops 1 for leave. However he was not cleared for Eyes or Atomic and a post, a flt lt, Ops 1a was established to cover the gap.
At STC, Ops 2 there was also SAC. When QRA finished he thought it was a shame we no longer had an practice alert exercise so, off his own bat, he introduced Exercise Edith to replace Edom. I don't know how that panned out as I departed shortly after.
In the other direction I think we might have had RAF pilots with the B52 training wing. As TO said, there were tanker exchanges.
As for trusting with nuclear weapons, I think that was the problem with UK weapons. The other issue is the employment of non-UK nationals on UK operations. The Icelandic Cod War was a case in point with exchange officers on the Nimrod being individually cleared by their respective governments; they all were IIRC.
Similar concerns applied in the FI and GW. For instance the German Government forbad play in GW 1 for NATO AWAC crews.