Well, for starters how about a housing allowance like the US Forces get?
This is a great idea. I was chatting with a USN exchange officer yesterday and she told me that they get roughly £750 per month as a housing allowance to spend as they wish, either to rent or pay a mortgage. The money for rent can be paid either to the US armed forces equivalent of DHE or go to(ward) private rental. She said this has had the added benefit of making the US Defence Housing Agency raise its game.
Such an initiative in the UK would cost around £180 mil to operate (12 *750 * 200000). I doubt this is even 0.5% of the defence budget.
I think such a move would have a massive positive effect on morale.