The conditions written on the airworthiness certificate by the approved person are law. SAAA APs will typically consider the risks associated with the test period including aircraft type, nominated test pilot experience, engine type, etc. I have tested two aircraft that I built myself. In both cases the test program was rigorous and useful in identifying rigging issues and exposing me gradually to the handling characteristics of aircraft types I had not flown before. It is not a tick & flick exercise. Carrying additional non essential personnel is irresponsible, in my view, in an untested aircraft. If you are not current or competent find a willing and capable person to do the initial testing for you. Many home built aircraft accidents occur when pilots have spent years and $ building an aeroplane and not flying and then take on the test flights.. In many cases they have built an aircraft that has higher performance and is more sensitive/responsive than anything they have flown before. The test program also takes them to parts of the "envelope" they have not seen before.