A space setting might work for an alien vs predator budget, even if you the same budget as an avp movie.
You don´t need to be in space all the time you can set it in a colony, shoot it on different locations on earth.

You could use a similar story as requiem, a pred-ship loaded with aliens crashlands outside a colony. The rest of the movie takes place on the planet, then maybe the last 3-4 minutes in space again. Its basically the same thing, maybe you need to create some cool sci fi gadgets and weapons for the colony and make some miniature stuff. They had miniature stuff in the first avp. Helicopter, the snow vehicles. Whaling station. The exterior pyramid!
Or just follow the comicbook, with Predators planting aliens on a planet to hunt. I would love to see that, not just for having it in space. But having it in the future, you can create alot of cool technology.
But i know Colin and Gregg are doing the best of the situation and i understand that fox is forcing the earth setting. I think the trailer for Requiem is awesome, the trailer alone is much better then the first film!
Btw. Im a director myself, work in sweden. Make lowbudget independent films.

I made my own little predator homage film a couple of years ago, a vietnam war film with werewolves. You can se the trailer on youtube:
http://www.youtube.com/watch?v=KxqGE9vXFzM/Ola