I wouldn't recommend it. Too short of an insertable length, not made of bodysafe material, and the flange doesn't have enough size difference with the body to ensure that it's securely held in a harness.
If you must then I'd go with one as close to 1" as you can get the dildo into.
we didn't try it with an O ring because of its size. Its so tiny that even if you could find an O ring that would be compatible it would take away on the length. The base is shaped just right that even in the wettest of conditions, it's easy to manage.