KwM: I sometimes do portraits with a Tech V, the rangefinder, and Grafmatics, and it is a fairly dynamic way to work in large format. You've got all the bellows draw you need on a Technika, but realize that the rangefinder only works over a relatively limited range. Still, it will get you close enough for most portraits, and the separate finder is not so difficult once you get the hang of it. If you get out of RF range, you can always switch to the groundglass.
If you are comfortable shooting portraits with large format on the groundglass, having the rangefinder to double check focus makes things that much easier. Tricks that some people use for portraits with groundglass focusing are a string from the tripod to the nose to confirm focus distance or a projector with a slide to project a thin beam of light on the subject's ear not visible to the camera. I usually focus, insert the holder, and watch the shadows on the subjects face carefully, and when they are exactly as they were when I focused, usually the head is in the right position. Now if I'm using the Technika and an interesting expression arises with the filmholder in the back, that's when the rangefinder is invaluable.
If the subject is very mobile, then the solution is to use more light for more DOF.