Instead of treating them like a hedge, why don't you think of them as trees? Open up the smaller branches in front of the windows so you can see out as much or little as you want. Whacking them off at just below the window doesn't seem right to me.
Mike

Yes, remember that anywhere you flat-top them they will immediately begin growing back up into the space they previously occupied.

You can prune and shape strawberry trees any way you like, they are very amenable to pruning. The above posters are both right. You can cut off the tops, but the plants will resprout with multiple branches at every cut and regrow. Thinning and shaping them sounds like a good option.