Well, yes, of course you can run Silent Hunter 4 with mods in Windows 8. It's just that Windows has added just a few more "features" to protect the operating system than what Vista had. It's not a whole lot different from Vista. Don't install the game into a "protected" system folder, which includes avoiding the Program Files (x86) folder. If you've already installed in there, you should be able to copy the Ubisoft structure and the game below it over to either the root, or to another folder of your own creation. That will allow the mods to alter the game. You should also run the SH4.exe as Administrator. For a lot of folks, we have to set our computer's display to the same resolution as the monitor, which is the "native" resolution of the monitor. On my computer, the screens are 1280x1024 @ 72 hertz, so the computer is set that way, and I have my game set to the same resolution. So folks have to jump through a few more hoops and set the SH4.exe Properties, Compatibility page to "Disable scaling on high DPI settings", in addition to the "Run this program as an Administrator". I don't have that issue, since my computer can't display above what the game can.
JSGME is v2.6 - (pay attention to folder structure, as noted in the JSGME ReadMe and/or instructions), TMO is 2.5 plus a patch, RSRDC is v5(??) plus a patch. (I never did quite follow lurker's numbering convention, but I'm sure it made sense.) Bleiente has a mix creation of his own using those two mods in
Ralles RealModPack for TMO_RSRDC_OTC, and there's our team's attempt at updating the AOTD_MadMax team's
Fall of the Rising Sun Ultimate, plus a myriad other mods, including modern sub updates, from post-war to cold war periods and beyond... cool beans, man.