If you have a good ignition, radio, and associated components, with components assembled correctly, you can almost stack everything on top of each other and still be fine.

However, do just one thing wrong and be prepared for trouble.

We generally use shielded ignitions, resistor plugs, and no magnetos these days and a lot of the warnings are based upon early days of gas engine use. Of course the safest way is to observe every safety precaustion ever developed but eventually you run out of space and distance, along with C/G allowances, to install components.

The final decision will always be based on the results of the range tests performed before flight.