Looking at the Henry Tripp (of Michigan but formerly of Bristol) who's the only person in the will explicitly linked to Bristol, as far as I can see. He seems to be the carpenter Henry Tripp who became a burgess in 1812 as the son of a mariner Henry Tripp. Probably the father was the Henry Tripp who married Hannah Bolwell at St Peter's, Bristol in 1780.
Then in 1791, a Richard Davidge married Hannah Tripp. The record doesn't say widow or not, so there's at least a chance that's George's parents.
David
PS I hadn't noticed that you already had the father as possibly Richard, that makes it more likely this theory is correct.