I have this big plan in my head for my next Skyrim game and I would very much like to hear the opinion of more knowledgable people, on whether this would be at all possible.

For our graphic design company we'll be purchasing a real Beast of a Mac in the next couple of months. Up to it's eyeballs in specks and graphic cards and whatnot. I thought I might as well make use of this for a bit of Skyrim time. I played on PS3 before but the lure of all those excellent mods (particularly Frostfall) has proven too much.

I've only played one character in Skyrim so far though I put about 300 hours into it, so the intro sequence is still very fresh for me, and I'd like to keep it that way.
My big plan would be to purchase Windows 8 for my current Mac, install Skyrim on it through Steam together with the three DLC's, then through Nexus the Unofficial Patches and the mod Alternative Start. With that I would avoid the intro sequence and create a test-character, which I would use to test the game very time I've downloaded a mod.
Then, when we get our Beast, I'd install Windows 8 on that, transfer all the Skyrim files and mods, uninstall Alternative Start, and start a new game in the normal way with all the mods up and running.

What do you think, does this sound like a crash waiting to happen? Would it be doable or am I better off forgetting all this nonsense and just installing those mods on the new computer after the intro sequence is done?

Any opinions would be greatly appreciated!

As long as you're not removing mods from a save game (so if you had Alternative Start and then uninstalled the mod and used the same character), then you'll be okay. Testing mods on a fresh character before your main one is actually a great way to do it.

Just remember to actually install Steam + the game on your new mac, then copy the files over or Steam will kick off. Also, while you'll want to copy the Saves folder in My Documents/My Games/Skyrim to keep your saves, you don't want to copy Skyrim.ini and SkyrimPrefs.ini in that folder as you want the launcher to regenerate those for your new install (they're very much hardware and software specific).

That is very good advice, I shall heed your wise words. Thanks!