Realistically speaking, after the deposit deadlines pass and movement halts waitlists are pretty much hopeless. The way I see it, after deposits, waiting on a waitlist pretty much amounts to this: Genious decides at the last minute to defer his Harvard acceptance, causing Prodigy to be wooed away from CLS, causing Einstein to get admitted to CLS and opening a seat at UVA, and the trickle continues downward.
What are the odds? By the end of July, if it were me, I would just let my waitlists go. You're literally praying for 1) somebody to suddenly decide at the eleventh hour not to attend, and 2) out of the entire pool of WL candidates, for some reason you're at the spot the lightning decides to strike. This isn't true if you're waitlisted in the same school you've deposited at, though.
Also: subleasing. It sucks, but it's an option.