I also shoot with a 4x5" view camera, and am DOF-challenged with many of my shots (camera movements notwithstanding).
I was wondering if Helicon Focus could help: I could take say 4-5 shots at different extensions, scan the chromes and combine them with HF.
Problem is, typical 4x5" color scans are H-U-G-E (I have access to a very high-end Creo scanner), this of course is welcome for large prints.
Which is the limit of HF in combining say 5 very large shots? Sometimes I read 30 MP, sometimes 50+?
I have a dual core Athlon PC with Windows XP 32bit and 3 GB of RAM (fully visible from Task Manager and Photoshop by the way: I used the /3G trick).
First of all, I don't think you will need so many megapixels, but I don't think there is a limit. It may be very slow with large files, but you have a good comp.
Latest 4.16 version of Helicon Focus handles big files better. I've experimented with 70Mp 8 bit images on 1Gb computer. As you know each process can work only with 2G under Windows, but this should be enought for your 50+ Mp images.