I've just found your message on the Dunn board showing Lewis and Louisa Ellen Dunn married in Iowa in 1881. This seems more consistent with the date of Martha's death than the marriage date in the Mormon records. Also they have the marriage in Texas Creek, Co. BUT would he have returned to Iowa for a second bride? (The Fremont site also has records of wagon trains to this area from Iowa.)
There was lead-mining in the area of Wales Lewis came from. If he was a miner in Colorado this may mean he was more free to move around than if he was, for example a farmer.
Any ideas where I might find more records of Lewis Francis Joel in US?