Thanks, reporting back: 113 is good but there was construction for about 3 miles where the shoulder was reduced to about a foot to the right of the rumble strip, not fun. In general though there's plenty of room between the rumble strip and the edge of the shoulder, with a few exceptions. Rt 12 from Snow Hill down was also fine.
The road from 12 to Chincoteague was okay up until just after the end of the NASA facility. There is no shoulder except on the bridges for that last 5 miles, and we crossed over on Saturday late afternoon and came back on Sunday mid-morning, constant traffic, mostly fine but a few impatient jerks.