I live a similar lifestyle to this. Since graduation from residency I have been out of state almost every month. I travel out of the country about 3 times per year. It is definitely possible as a staff ER physician. What will limit your ability to do so more than work will be your family life. If you are married and especially if you have children it will be a different story. I have no children and my girlfriend also has a flexible career.
Another note: One poster on this board (I forget who, I'm sorry I cannot give credit where credit is due) had a very brilliant quote. They said (I'm paraphrasing) "As an ER physician you will have enough money to get all of the normal stuff (save for retirement, pay off loans, daily expenses) PLUS one 'prize.' This prize can either be a awesome material stuff like a huge house and a fancy car, amazing vacations/travel, or a non-working spouse. You cannot have all 3 of these."
For me I have opted for the travel and vacations. I still live in a small apartment, drive a 10+ year old econobox car, and my girlfriend works full time.
Ultimately it comes down to your priorities. You will have to determine your own balance of work hours, free time off, and expenses. The great thing (and I would say BEST thing) about emergency medicine is that you are free to make this decision and decide. My most miserable partners I would say are those that have financially over-reached and are now working more shifts than they want to cover these additional expenses.