I'm going to reiterate what's already been mentioned above, but I'm going to actually give you examples of why it's relevant to you to find a U.S. tax professional.1 - You're going to need to file U.S. taxes once you have property down here, there's federal filings, state filings, and sometimes local filings too2 - Tons of tax treaties between the U.S. and Canada that are easy to miss and can cost you a lot of money (important one with rentals - effectively connected income - if the professional you talk to doesn't know what this is, run away)3 - The amount of days you spend in the U.S. needs to be tracked and if you go over a threshold, all of your worldwide income could be taxable by the U.S.4 - Selling real property means up to 15% of your sales proceeds might not be available to you for years (FIRPTA)5 - Lots of nuance at the state and local levels, which both want to take as much money from you as possibleMain takeaway here is that you should find a U.S. based tax person.

Meet with a local banker & schedule a time to talk with a mortgage broker, they'll give you at least a baseline of what kind of down payment options and rates are out there.After that, if you're still wanting to research more creative options, do some looking into seller financing (a very hot topic with good, and bad, advice out there), look into private lenders, and commercial financing options.If you're wanting to live in 1/4 of your quadplex, then conventional residential loans may in fact be your best option as you can purchase that with a fannie/freddy loan with very low down, and use up to 75% of the income from the property toward your own income. 

Given your experience with RV parks and MHPs, you already have a strong foundation for managing mixed-income streams, which will be valuable here. 

They mentioned they didn’t need any income.

St Cloud MN Duplex, list/purchase price $259,900market rents $1,610 per unit BUT yes, if one really wanted to sec8 income standards are $1,957 per unit so one could go that direction if wanted be.

If you don't care about income and are more of a capital gain kind of guy, prices are already high (as you noticed) and there's plenty of land available to buy so I'm not sure how much is left in the tank.

Lost Income- normally 18 to 24 months. 

FHA now allows us to count rental income from an ADU (additional dwelling unit) to help borrowers qualify.

The rates are high right now but these loans are limited based on cashflow so you cant take a loan that costs more than you're receiving in rental income.

Correct - Track all your income and expenses.The bookkeeping will determine whether you are profitable or not.it will also be good to compare from year to year your income / expenses to see what expenses you can potentially try to limit.I.E.