One thing I didn't see mentioned that we always do on out of state or out of country projects, is to Skype or FaceTime with the company you have hired to pull wire or do some of the install. Have them actually walk around the site with the computer and show you the installation.
This way you can actually look for any issues, before they become ISSUES.

On the last out of state job we did, I took tons of pics during the walk through. I marked everything (speaker locations, data ports, home run, demark & TV locations with client and electrician.

We drop shipped all prewire parts (wire, HDMI cables brackets and rings) and the electrician ran everything as per our "written" plans. Client took and sent pics before insulation.

For Trim/Final, I hired a local CI tech for additional manpower and drove out with what I could fit in my truck and drop shipped whatever I could. Install took one long day. My programmer pre programmed RTI remote that I brought out and it worked like a charm.

Client preferred I stayed in their guestroom instead of paying for a hotel for me. They were very happy with the results. We watched a movie on night #2 and got drunk with them. Early ride home the next morning. I charged our regular labor rate, and fuel (not drive time of 12 hours both ways), they paid for all meals.
Would gladly do it again.

Every job is different and so the contract changes as well. In general. All time spent traveling is billable. I push for a full rate but have done a reduced travel rate on some jobs. Anytime flights are involved longer than 3 hours first class is required. Irs per deum rates and mileage always apply. I’ve done a flat daily rate of say $1000 -1500 day. As usually when out of town the days are long The point is if your traveling for work make sure it’s worth your time as you can stay home and make money much better easier. But for the right client.....