No harm in running duals on pavement in road gear on an H. Dad made a set of clamp-on duals for my Stg II Super H to plant corn with and I ran it to town a couple times with the duals on to get hog feed. The added width of the duals just made doing chores a bit harder. Used to run the half mile between farms in road gear with duals on all the tractors too. We ran the duals for the last four years Dad farmed with no problems. Just had to check the turnbuckles every morning to make sure they were tight.
I'd run 4-5 PSI less air pressure in the dual tires than you have in the main rear tires. Keeps stress on the wheels & axles lower.