I’m sure others here are also running into this issue, so any recommendations and referrals would be greatly appreciated!

The members here on BP that talk about STR auto-run systems didn't install those systems and find dependable cleaners & handymen overnight.

At least run this with good, bad, worst scenarios.

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.

I would just cap it generously to only catch abusers and figure the normal running costs in your rent. 

And DIY repairs are not recommended for other reasons: it will take you much longer to complete, depriving you of rental income, and you run a high risk of your wife becoming your ex-wife.Same risk exists if you push your wife into becoming a Realtor or some other real estate activity just for the sake of tax benefits.

Based on my experience of running properties, even if the build were to cost you as much as $600k but you could generate $125k/year, you'd be very happy with that investment. 

Just focus on running the numbers carefully to ensure the property cash flows or at least covers expenses, and don’t hesitate to lean on resources here for advice.If you’re financing, look into FHA loans, as they’re great for first-time buyers purchasing up to 4-unit properties with low down payments.

I have been to RE meetups in the past with like-minded everyday investors pursuing similar goals, sharing stories and learning from each other, running through numbers, sharing network contacts, and even doing deals together.

The monthly payments are great, but the issue I am running into is what to do with idle cash.