I think the act of being apart keeps the passion going. Since my husband became a trucker the intimacy when he gets home has increased by a large amount.
We keep in touch with a minimum 20 minute call a day.
During the rest of the time its by text. I'll send him a thought via text or a picture text of something that caught my eye. Sometimes its a picture text of the cat sleeping on the couch, or a picture of one of my parent's cats that he likes, or an impromptu pic of a group of us together hanging out. I've even sent him pictures of random family dinner tables of meals that he's missed out on. All those things are my way of keeping him connected to the things he misses out on when he's gone, but he knows that we're thinking of him.
As for masturbating while apart is concerned. I know he looks at porn and masturbates. He knows that I have vibrators to be used when he's gone. He tells me when he's watching videos and I tell him when I use my toys. He knows that my line in the sand is that I won't use my toys while on the phone with him. He respects that. We've had to experiment a bit to figure out where the lines get drawn.
Knowing what your wife's comfort level is, try communicating and experimenting and see what other things she's willing to try before reaching the top of her comfort level. Don't forget that this involves TWO people, not just what YOU want.