Joe, I've done many and watched many being done at...
the restaurant I used to work for. Trimming is very important, especially if there is any silverflesh. You won't get uniform steaks all the way down the length, you'll get into the smaller end where you have the petite fillets, and then the tips for stroganoff, etc. But you should be able to measure out 12 steaks fairly easily from a whole tenderloin. You can also get creative with the bacon wrap if pieces aren't staying together if need be.