I had the same problem last year, with stray cats invading our yard and upsetting our cats. I found an item in a couple of catalogs - one was Lee Valley, and the other was Home Hardware. The item was called motion-activated sprinkler. It looked like the ideal tool for the problem, just a tad expensive though.
I put a ball valve on the outside faucet so I could turn it on quick when the backyard became invaded with unwanted cats. This system worked quite well when I was at home, and it seemed to solve the problem to a degree. If this problem starts again this summer I may have to invest in the motion-activated sensor. Here's Lee Valley's website for the sprinkler.
And here's the Home Hardware website for the sprinkler
Lee Valley also has another tool called a CatStop. It would be alright if you didn't have a cat in the house, due to the fact that it omits a high frequency sound that would repell a cat, or any other animal whose hearing range on the high-end is between 21 and 25 kHz and the sound is at 124 dB which is quite loud.
Check out the SSCAT cat I think you'll find it is more designed for inside use. I understand it works quite well for certain applications but the range is only about 3 or 4 feet. Great for tabletops, counters and other close quarter areas. Check it out - it has been a few years since I looked at it and it could have changed.
The motion-activated sprinklers I would expect would be in other hardware stores as well, might be worth looking into.
If it was me, I'd be using the Feliway in the bedroom to help with the stress, until you can correct the situation. As far as the "cat-away" sprays are concerned, if they are a scent deterrent and you open the window, the smell will drift in and have a similar effect on your cat - deterring it from using the bedroom. Don't forget that a cat's nose is about 14 times more sensitive than ours.
Hope this might give you some more ideas.