I think it is noticable that all the dominions are in areas that were suitable for european style agriculture and as has been noted above started out with a low population density. This encourages early British immigration and european style society and culture. The problems with most other colonies is that they were difficult to occupy, settle and farm without late 19th C technology and were often occupied by strong populations with their own agriculture, society and languages.
A dominion hacked out of the jungles of say the Congo is just not on without changing British society so much the result is not really a British Dominion.
However there is one obvious place with good european style climate and low population in addition to those mentioned above.
California. Simply get some sort of minor British settlement before say 1790, perhaps a penal colony like Australia or a whaling protection fort and then wait a hundred years.
A dominion hacked out of the jungles of say the Congo is just not on without changing British society so much the result is not really a British Dominion.
However there is one obvious place with good european style climate and low population in addition to those mentioned above.
California. Simply get some sort of minor British settlement before say 1790, perhaps a penal colony like Australia or a whaling protection fort and then wait a hundred years.