Just did this a few months ago. Its really easy, just measure a million times and cut once. The laying of the subframe under the truck frame is by far the recommended way for people who don't attempt fab work often. Doesn't look the best but I plan on boxing it in and dressing it up to look better. Plus if you plan on laying frame it gives you something to drag instead of your truck cab.
With that said you can't even see it unless you plan on putting mirrors under your truck LOL.