What Academy do you attend? My youngest Son just graduated from Faukland U's Army ROTC program and is now a 2nd Liutenent (Quartermaster Corps). It's hard for me to fathom my 22 year old walking out of school into 48k + yrly. But hey...he earned it! (3.997 GPA too!) Good luck to your plans!
An "Acer" eh? 720p? Zounds! You don't state which model you posses, but upon checking, the 720p DLPs they have range from 2200 to 4500 lumens.
OK...., I'm gonna suggest something I virtually never do, least wise not on the DIY Forum.
Get a "el-cheapo" manual Pull Down screen.
No "Cloth" that is not significantly "bottom" weighted and formed to be flat will do your situation justice. You could acquire some Black Out Cloth and using the shiny side, get a decent image, but unless it's stretched across a rigid framework, the wrinkles and folds will distract terribly from your viewing experience. Even "Waves"....slight variations of height (distance) from the wall will be quite noticeable.
The darn things cost just over to just under $100.00 on some web sites. (...yeah...a LOT of $$$ for a Student...) Below is a link to a 16:9 unit. A Web Search will find others for less.http://www.projectorscreensdirect.c...Go.x=20&Go.y=10
Retracted, it will fit easily into a closet or under a bed. That is if "Inspections" would not take issue with such when it's stowed away neatly, out of sight..
Here's a plus. Unlike a Wall (see below) you can paint that screen with a Contrast enhancing coating, increasing your perceived CR considerably (Acers max out at 2500:1) if you want the room to remain "lit". Depending on which Acer you own, you've got lumens to spare, but those lumens, when reflected off the screen (or wall) will also splash out and onto every white surface around you, further reducing your observable "On Screen Contrast"
The other option is to get permission to re-paint the walls a clean shade of white. If possible, that would be the easiest route to take, owing to the fact that no "set-up / take down / stowage would be needed. That should be do-able. Just ask the OD as if you want to improve your room's appearance for Inspection.
Of course, if all the alternatives are crap.....then rolling out some BOC and hanging it on that Velcro is gonna work to some extent better than a poorly painted wall. Maybe. (...you'll have to take down the Velco too, yes?) I'd say you just gotta try that Acer out on that wall first, no matter what....then go from there.
Beyond all the above, I suggest you also ask the question of "where can I find a Cheap Pull Down Screen?" over on the "Screens Forum" because around here we are best suited for, and focused on true DIY applications. If you want to continue along in that direction, that is?