Utah... ahh yesh... I remember it well... 1994, the wife and I flew into Vegas, rented a van, and did a two-week round trip through northern Arizona, up to Durango, and across Utah, hitting 11 of 13 National Parks along the way... how close to Capitol Reef are you? We gotta get back out that way, and see the hoo-doos, the Arches, the Patriarchs, National Escalade and everything else that beautiful state has, not forgetting to mention the nice people, of course...
In the meantime, you can mod the Steam version of SH4, but it's much easier to do if you don't have the game installed in the Program Files (x86) folder. If you do, you have to turn the Windows UAC way down, among other things, if it'll even do it then. It all depends upon your computer set-up and the OS. If you want to re-install to a "regular" folder, such as a "C:\Games\Silent Hunter" or similar (I just delete out the Program Files part anymore, and do "Ubisoft\SH4"), you have to log into your Steam account, and use their online install manager to direct the install away from the "default" Program Files thingie.
Welcome to SubSim, btw