You have to maintain visual contact with your aircraft at all times or if you are using goggles, a spotter that has the ability to assume control does. FAA regulations require you to see and avoid all full scale aircraft. If you can't see your own aircraft how can you avoid something approaching you from the side or rear? Also, your transmitter and aircraft receiver will limit your distance to < one mile line of sight distance max. If something gets between you and the aircraft, that distance can be severely decreased. Also, a typical video transmitter, let alone one that would get your signal back to you at your proposed distance, requires licensing. Any of our typical VTxs need licensing to be legal. In spite of what is advertised, currently Amateur Radio licensing does not even allow what we typically use as FPV (e.g. No VTx Station ID, No one-way transmissions are allowed, etc. etc.) But there are a lot of folks out there doing it anyway in spite of the regulation violations and the resulting $10K+ typical fines for violating FCC Regulations.

Lots to think about. Most folks are NOT doing that thinking first. Eventually, there may be a full scale plane hit by one of these illegal long distance FPV aircraft and the regulators may shut us all totally down. Yes., ... there are a lot of folks operating outside the limits of their FCC Licensing. Eventually, the FCC with either get their regs caught up with the technology or they will start dishing out some enforcement. Bottom Line until then: What ever mode we are using, we have to see and avoid all full-scale aircraft. They have the right of way at all times! Stay indoors or stay low. Use minimum power necessary to communicate. Stay 5 miles away from Airports, unless you have the capability to integrate with full-scale traffic and the Airport tower knows of your presence.