None of the car holders I found would accept the S5 with a case and none of the wireless chargers would mount in my car so I designed and built my own. I started with a TYLT angled wireless charger and removed the electronics. I did some measuring and made a slide in "pouch" out of acrylic plastic for my phone with the case on. I glued a small box on the back to hold the circuit board. I used 2 pieces of foam to hold the board firmly away from the back which has a slot for the suction cup mount to slide into.
To make the I cut and taped the assembly together then just put a few drops of solvent into the corners. It wicked in and held firmly.
While not pretty It works very well. See the attached photos. I may paint it later. No more squeezing little clamps on the phone or plugging in the cable!
Have you thought about using kydex? It would give it a very awesome custom made fit. Also it is very easy to work with. You pretty much cut the size you want and heat it to form fit it to your phone with a blow dryer. I'm thinking about making one for my car but probably without the wireless charging. I don't know how I would engineer that into kydex lol.