Co-founder of Bastin and Willetts Canada Immigration Services. Well placed to support entrepreneurs entering Canada via the Start-up visa program - lots to say about this program! Experience with LMIA and work permits, express entry and Family Class. Past life as a Serial Entrepreneur (Built one, Sold one, tanked one completely). Grew up suddenly, endured my own personal immigration nightmare and decided to memorize IRPA. Best serve Immigration Clients because I've been there, and I'd like to help them avoid 'doing that'.
I am a Canadian Immigration Consultant, and cannot advise you on USA Immigration matters. However, in terms of ethics, your path to legitimate immigration is not via a marriage of convenience. If you have the chops to make a start up work, that is legitimate. If you have a job offer and can proceed via the L1 visa, then this is likely your least complicated route. "Ethical" immigration is universal, and so I my answer is given to you in this vain. Marry for love, not a visa!