Been in your shoes. The old Ansco I was using went bad and died half way through a four week cross country tour. Rolls and rolls and rolls of color film, blank. Hopefully you chimp and found the problem quickly. Another advantage of digital.

Everyone talks about the weight savings of the mirrorless cameras. From what I have looked up spec wise, the weight savings of comparable cameras is rather small. If you compare FF to APS or 4/3, then yes they are lighter. And smaller. Just saying, check the specifications.

And while you are checking specs, see if Nikon makes an adapter for the Z body to your Tamron lens.