I am trying to understand what is required for proving certain expenses, repairs, and supplies for a rental property I rent out.

I have a full-time job, so managing this rental is something I do on the side.  With that said, in the last year, I've had to drive there 10 times (230 miles round trip), bought supplies (cleaner, tools, etc), did lots of maintenance and repairs, and made a few significant improvements (which I know get handled differently).

My main question is what do I need to prove my expenses were relevant?  Some of the receipts I have don't show itemized lists of everything, but my hope is their clear enough (like a motel receipt I have just has the motel name, date, and charge).

I also bought some inexpensive furniture for the house second-hand, and have hand-written "receipts" from the sellers, but imagine those probably aren't sufficient (though wasn't sure what else to do)?

Even for the trips themselves, I can prove I was in the town where my rental is on 10 separate trips given my credit card and obviously the mileage between my home and there can be easily verified, but how do I prove that I actually used my car for all of those trips?  Is that necessary?

To any advice on the what the burden of proof entails for stuff like this would be much appreciated.  Thank you very much in advance.