oh ... complex situation
Complementary thought to the separate box idea (I type too slow - was beaten to it - lol )....
Are you running 10 Pro, and if so, do you have a legit copy (i.e. not been upgraded to 10) of Win XP/7/8 ? (i.e. whatever Win release your version of PSP used to happily run on)
If so (a huge if i know), Pro's Hyper-V virtualisation is good and you could run a XP/7/8 virtual machine just for the purpose of image editing.
A pain I know, but the workflow would remain the same and all the old psd's would be usable - might save many hours .... and might waste many as well
[ before I get jumped on by the linux club, VirtualBox et al is good as well ]
Yep I own a legit un-upgraded Win7 Pro as well as this copy of Win 10 Pro. I have a SSD disk which is my old system untouched, but still have the DVD too. When my old SSD drive died I was sent a new one which is still blank so had a spare.
Hmmm you just gave me another thought ... my case has some sort of dual boot system switching. Need to look further at what it can do.
Scrap that easy option - only works with traditional 3.5" drives. I guess that doesn't include SSD :/
Need to sit down at some point in the future and consider the best way forward.
Dual boot or virtual box could be an option. I have spare 120GB SSD not any HDD's.