No. You must ground the airframe as well to prevent electrostatic buildup and to shunt lightning strikes. It's likely that many of the electronics items have a protective ground connected to their metal case that can benefit by being attached to the airframe (which is grounded). Of course, most antennae have a shield that must be grounded to the airframe.
There are two or three schools of thought about using the airframe in an RV as the ground return for electrical circuits.
Firstly is your method to provide individual grounds for all circuits. Lowest potential for electrical noise, but more than doubles the weight of power wiring (larger wire gauges x twice the wires). Also, more costly.
Secondly is using local grounds to the airframe. Lightest weight, lowest cost, but can lead to more electrical interference and audio noise.
Thirdly is a hybrid system. All audio connections use a single point audio ground and shielded cables. Noise generators (strobes, some LED lights) also used shielded cables and individual ground wires in the cable. Benign loads such as pumps, incandescent lamps, heated pitots and so on can use airframe grounds. So can the main battery. Keep avionics on a single ground point whenever possible.
Some will object to the potential corrosion effects of passing ground current through an airframe. Use the method in AC43.13 for the stack-up of washers to mitigate this at the points of connection. As for rivets passing large currents... I will defer to another authority, but I've never seen same-metal rivets corrode due to electrical currents in an aircraft.
V
p.s. the term 'Ground' when used in an aircraft can be confusing. The term 'Common' is more correct, but, uh, less common. Back in the day when I used to receive updates to my AIM/AIP that had to be inserted manually into a binder, some overzealous bureaucrat in Transport Canada decided to replace the term 'ground' with 'common' in the regulations pertaining to electrical systems. While technically correct, it required hundreds of pages of regulations to be replaced, often to replace a single word. Aside from TC having to print and mail this information to tens of thousands of pilots, we had to spend hours replacing pages in our binders.