breezeway collar ties

Snow is not the only load, there is also wind, which can be a sizable load. Even without those loads the natural tendency of the un-tied rafters is to push the walls apart. As I said before, a catastrophic failure is unlikely - it's not a crucial structure (particularly to me!) and you could assume the risk since it's your house and your money.

Your plan of supporting the ridge and tying the rafters together sounds like a reasonable solution. I'd suggest that tying the plates together would work just as well as tying the rafter pairs together as long as you've made adequate rafter/plate connections. That would also enable you to place the ties exactly where you want them.

I don't know, but I ran across this article which might give you some ideas regarding snow loads.

Tieing the two top wall plates together every two or three feet should work just as well. If the walls can't move out, the roof can't come down.

Anthony