Just to say part of the above in a different way:
Film cost is highly variable, depending on volume. You need to figure out your probable film use - 100 sheets 4x5, 1,000 sheets, etc. Then figure out what the "breakeven" would be in film/supplies to get a comparable digital kit at that quality level.
Look at yearly depreciation for the digital, not total out of pocket cost day 1 (It is a capital item)(Buy for $20K, use 3 years, sell for $8K. Net annualized cost is $12K/3 = $4K per year.)
You could also make digital cost less fixed and more "variable" by renting for 1-2 days if your shoots are long planning, short production (like 2 months building a set and doing "test" shots, then committing the final image to film/hq digital on 1 day.)
The part of photography I like is wandering and making images, so I am a "high volume" type shooter. Paid work tends to be fashion, which is also very high volume.
Look at the people producing the size and quality images that you envision. Paul Shambroom, Alec Soth, and Andreas Gursky and Gregory Crewdson at the extremes ($250k budget, camera operator, director of photography)
Then - test! There is a steep and costly learning curve to get to those gallery quality 2x3 meter prints! Capture is just the start .....
Fwiw, I shoot my B&W images on 4x5 color stock. I really value the ability to tweak grey values by "mixing" color translations in Lightroom at conversion time to B&W.
What seems to fall out above is: 4x5, or even 8x10 (Soth, older Shambroom, etc. ) For digital, stitch 35mm FF, stitch 22 or 35 MP MF, rent 60 MP on a daily basis.
Will you be able to sell the big pics for $5k US or so? Do your paintings bring good prices? If so, you are able to "leverage up" based on your current and anticipated income.
On foxes: when I was 17, my girlfriend kept asking me what a "fox" was. Some guy was hitting on her and calling her that. She didn't know what it meant.
She was, I was not. She had a tendency to "stray" with all the guys hitting on her all of the time. Better to be with someone you trust ....... There is a current song here to that effect. I'll find lyrics to quote.
Good luck!
Michael