Neither the Taconic nor Merritt Parkways are suitable for any large motorhome. Do not do it. I checked with the State Police: while they say it is permissable to use them (noncommercially), they do not get it - your size. I couldn't get through the entrance toll booths and traffic had to be backed up for me to go through the end booth, (raining on Thanksgiving eve, with a 33' Foretravel) despite what the state police barracks had said over the phone. As has been pointed out, the primary problem is the overpasses (stone bridges). Don't do it.