I met a few guys doing it when I did my British coastline ride.
Most were supported. I,d take 2panniers, as I do usually. It's very busy with old cars,motorbikes, and damn motorhome rentals, not a clue how wide they are!
The passing places are a pain for a biker.
As has been said before its hilly, yeah no probs. Midgies? Yes. There is places to top up food etc, as it's getting popular.
Shame your not using the A90, such a lovely route by the coast.
I rode very early in the morning. Avoid the traffic.
Scourie, a little place on the east has a cycle repair guy, maybe worth noting that, as I needed it.
Good luck and enjoy it.