Instant Film for 4x5
After shooting some nice (to me anyways) landscape/cityscape images with my 4X5, I want to return to my natural habitat and start doing portraits with 4x5 (it was a nice hiatus).
Trouble is, I typically use 1 or more strobe flashes, with various modifiers, on a "set" (might have a still life going on in the backgroud, or maybe an interior shot with 2 persons, as an example), and while I don't have any issues with regards to metering, focusing and composition, I am worried that I won't be able to reliable predict shadow contrast and how the light will interact/fall between various objects and the main subjects on the set (the modelling light is useful, but other than the fact that you'll set your subjects on fire, it isn't totally reliable or accurate IMHO - it works better when the set is really dark, but I don't always have control over that).
I always had in the back of my mind that I would shoot Fuji instant once I got everything set up, but I found out this morning that Fuji instant isn't available anymore in 4x5 sizes. As far as I can tell, most studio photographers using film back in the day (from what I can find on Youtube), typically take a few polaroid check prints before putting a final image down on film, so I know I'm not the only one who is concerned about light when using strobes.
Are there any practical ways around this? Does it make sense to use the smaller instant film size or should I just keep 4x5 for landscapes and use medium format for portraits (I prefer not to!).
Any help would be appreciated!