I would think a mayor with 'strong powers' could propose, amongst a long list of other CIty initiatives to pay for itself, a set of tolling fee's geared to the upkeep and improvement of the the Gardiner/DVP combination. The tolls do not need to be punitive, unless we are geared to forcing people to adequate regional transit (which needs to exist first), in which case the tolls could be shared with the agencies providing that transit. I would be onboard with that completely. (and also to toll other GTA highways to supplement their upkeep and improvement but also to flow funds to regional transit.)
I'm not sure why you would not toll commercial vehicles as well. Why would they have special status?
We should be wary of traffic leaving these routes to use inner city streets to get to destinations. I am not sure what % or drivers that might be, whether its a valid point of consideration, nor that we should not toll just based on that consideration, but it would be worthwhile having some knowledge of the consequence to tolling.
As a former city dweller, who is now a 905er but works, lives, commutes, employes throughout the GTA, I often think that transit (in all its forms) should be regionally based. Forget the TTC, how about the GTATC, forget about fares stopping at municipal borders, and bus lines, subway lines, streetcar lines etc etc. Tax and toll throughout the GTA to support the various forms of transit that may not be all centered on Union Station, but are based on moving as many people as quickly as possible throughout this region in a seamless fashion.