I think there are two issues that need to be dealt with.
- An alternative PTT scheme. VOX just isn't always the way to go. Could a flex sensor be used to pick up a unique body gesture that is not considered unsafe? Such as a shrug or a flexed finger?
- Automatic repeater handoff on long trips. As I understand the regulations, it would not be permitted to change frequencies, so unless one is willing to pull over each time he or she switches repeaters, a trip from, say Toronto to Kingston could lose contact pretty quickly as the Toronto repeater is lost. A combination of a micro-controller, GPS, CAT radio control and a small database of repeaters could make this process pretty seamless.