If I understand correctly, you want to utilise the swing/tilt to achieve a certain look for portraits.
using fast lens while combing tilt/swing might be an overkill, but all depending on your desired final result.
If you can show us what you aim to achieve, that might help someone comes up with a feasible solution.
I can guess what you want to achieve in your portraiture. I guess you want a portrait where only eyes are in focus and other parts of face out of focus.
I agree with guphotography that using very fast lens with much of tilt might be an overkill. The more you tilt the thinner is the focal plane. And it becomes more a wedge than a plane or a plate. The wedge is thinner near to the camera and becomes broader far from it. You can get what you want with 4/80mm lens and 15 degrees of tilt.
I don't see any reason why not use your 4x5 view cameras. It's not so important how many degrees of tilt you use or how precise is your focus or other settings in that kind of portrait shots.
You only need to mount your 100s to the rear of the view camera. If you already own those view cameras it's the cheapest way to try this.
In that kind of portraiture the most important is your shooting technique. My recommendation in order:
1. Put all movements to zero in the view camera
2. Focus to infinity or very far a way.
3. Screw in 8-20 degrees of tilt forward. ( That's a lot, it really makes sense! And it's the easiest way to start to put tilt forward, later you can rotate the tilting angle. )
4. Now it's the time to call your modell in and to try to set the focal plane to the right place. It means trying and error. Maybe a good idea is to focus "nearer" with the view camera. I mean to add the distance between the lens and the sensor with the view camera( not focusing nearer but setting the focal plane more horizontally). You can try to set the focus to you subject's eyes by lifting or lowering the camera.
I recommend you read http://www.trenholm.org/hmmerk/index.html#TIAOOF
and maybe you should install Lumariver app in your smartphone