Sounds like a projector is the wrong tool for the job. Is this a mobile presentation setup, or single-site? If the latter, that $5k budget could buy a 63" plasma display and wall-mount bracket, with a grand left over to buy a very nice lock for the front door. Intense colors, no viewing angle constraints.
Someone -- it may have been Sony -- was experimenting a few years ago ago with a display screen that contains microprismatic crystals which almost completely reject passive lighting while intensely reflecting the RGB output of a projector, but I have no idea if that technology went anywhere.
Abacus Model 2.5 | Quad-Row FX with 256 Cherry Red Slider Beads | Applewood Frame | Water Cooling by Brita Filtration