He should be able to pay rent regardless if he's on travel or not...he's an adult.

And, Can I still write off some business expenses related to my investments, e.g. business travel.?

Hobbies/interests include travel, hockey, golf, snowboarding, sailing, and drinking craft beers. 

Travel? 

Now if it is traveling data inputting, I totally understand that.  

I have no issues traveling an hour or more away from the metro area for deals, but I'd like to stay within the DC, Arlington, Baltimore areas.

@Bob Bowling - To be honest, it comes from growing up and traveling through small towns, and the "rent-mindset" of a lot of people.  

Not sure if he will travel that far but you can ask.

I travel there frequently and have many contacts/friends down there as well.  

However, if you're a late teens to mid 50s couple -- peak traveling ages mind you -- and there is a small % you may conceive, even if unplanned, then many should and/or would think twice going tropical.