Level 15

Business & farm

Since you can identify expenses related to 100% business you should be able to deduct those expenses.

Here's why I disagree. @Phil specifically states:

Trip Primarily for Personal Reasons

Per IRS Publication 527 at https://www.irs.gov/publications/p527#en_US_2018_publink1000218997

Travel expenses.

You can deduct the ordinary and necessary expenses of traveling away from home if the primary purpose of the trip is to collect rental income or to manage, conserve, or maintain your rental property.

So based on that, since Phil makes it clear with no room for other interpretation, the primary purpose of the trip was "not" for the rental property, not a penny is deductible as a rental expense.