I've done something similar to what you're contemplating. This is my second build and I have followed Nuckols both times. I used Z-14 as a guide for this plane.
I kept the standard PP alternator from Van's. It's belt driven up front and is internally regulated (which is fine since it has the ability to have the field circuit disconnected from the cockpit).
I added a second alternator from B and C along with the regulator. The alternator is mounted on the vacuum pad in the rear above the right mag. I got the BC410-H 20-40 amp which clears the oil filter and also does not interfere with anything on the firewall in Van's RV-14 plans. I expect to get a nominal 30 amps at typical cruise RPM.
I used the LR3C-14 controller instead of the the standby version. If I'm going to have a second bus it might as well be active. Almost all of the Garmin instruments have a second power lead with a built in diode so that they can be connected to two isolated busses without back feeding. I use some bridge rectifiers to get dual power feeds to the 625 the com and the AP servo's. The AP servo's get a dedicated switch to kill power to them if need be.
Here are the bridge rectifiers on way overly massive heat sinks. They could probably just be mounted to the aluminum subpanel directly, but I got these for about a buck a piece at a surplus store and they look very old school.
If you build it with two alternators and two batteries you should look at his Z-14 drawing. This allows both busses to be operating full time and can be cross fed if need be.
I mounted the regulator on the cabin side of the firewall just behind the rudder pedals and low enough to get at from underneath the panel.
The second alternator will have enough power to run everything including pitot heat. Since I have pitot heat only for inadvertent flight into icing, the emergency already exists if I need it and I should be looking to get out of it immediately.
This is the fuse panel I built.
Note the two ATC mountable resettable circuit breakers for the alternator field circuits. Here is the back.
Here is the location of new FF equipment required for my installation. Note, these contactors are for bus cross feed and external power. The wiring is just temporary here.
I built a battery box under the passenger seat with a local contactor.