The Epson will do the job the X11 has quick corner and is at the moment very cheap, but the problem you will have is most projectors are ment to be kept as level as possible to allow the lamp to operate properly if you incline the projector more than 20 degres it will shorten the life, but in your case i cant see any other way you can do it unless you go to an UCF projector like the Hitachi 221, your other way around is to mount it on a movable lift frame (board as well) so it can be lowered when in use.

Projector Engineer