combining diablo trinity with PLX wideband?
 

Theoretically, If I had a diablosport trinity tuner, could I connect a PLX wideband input to it, and get accurate wideband fuel info through the trinity?

Then, if I logged a bunch of engine data with wideband support, could I send it to a mail order tuner, such as jannety or *******, and get a pretty good custom tune?

yes... the Trinity has an input that would allow you to do that... that way you could log the wideband AFR together with the other necessary parameters...