I tried to overcome that objection by explaining that, unlike a LTR, STR's are professionally cleaned almost weekly and during that time they are inspected for damage and if any, repairs are made immediately.

You can use your money however you like, but it will still be taxable.Highly recommend sitting down with a tax professional and figuring out your exact situation.

You did not say if you are going to hire professional installers or do it yourself. 

An important quality I look for when working with Title Companies is their ability to problem solve, be dependable and responsive and have a polite and professional demeanor when interacting with me or anyone else involved in the transaction.  

You can find local professionals through this site, by going to the "Network" tab and searching "Members."

@Jay Hinrichs Buyers and sellers never need a ”real estate professional.”

According to this website, Citi cards are the best for extending the warranty: https://thepointsguy.com/guide/best-cards-for-extended-warranty/.I read the exclusions on the benefits/disclosures brochure associated with this card, and the only thing I saw that wasn't covered similar to what you're referring to was "Items purchased for resale, professional or commercial use." 

I would either have it professionally done, or remove and replace in your situation.

Eventually when you do sell without a 1031, you will pay US taxes but will not be able to use all the tax credit with the CRA.Finally, this is not an area to get advice  from non professionals (like me :).

The entire cost during renovation might not have to be capitalized and can be expensed, but you need to talk to your tax professional and give him all the detail.