> ->>Can anyone recommend a sheet film tank (loaded in changing bag)that
> ->>functions in the same way as an ordinary rollfilm developing tank?

Nikor (not "Nikkor") made a stainless-steel daylight tank with a reel
that would hold 12 sheets of 4x5 film (the tank takes a little over
a quart to fill, so chemical use efficiency is good). It is easy to
load, though I would recommend lowering the reel into the filled tank
for best results. I have three of these, and would sell one.
Hope this helps.