Bump Friendly Formal Attire?

I don't know about you all, but I can't believe it's October!!!  I mean, seriously, where did September even go?  Believe it or not, though, it is here and I guess it is time to start prepping for all the October fun.  At the end of the month, Josh and I will be leaving Colton behind (I'm sure there will be much more on that later!) to travel to Orlando for a work thing for him, a pool thing for me.  One of the events on the agenda is the franchise-wide formal affair that is held on the last night we are there.
Ironically, I have an old prom dress of my sister's that I have been holding on to for the last several years to wear if I ever had the need, but both times I have attended this function, I have been knocked up and the aforementioned dress is just not flattering.  I tried it on this weekend just to make sure (it is really stretchy after all, so I thought it might by some miracle of miracle work out), but no bueno.
So, now what?  There's a couple problems with trying to find a formal maternity dress.  For one, there is absolutely nowhere to shop here in Va. Beach for such a thing...we don't have cute maternity boutiques or anything outside of Motherhood Maternity.  And mainly, a formal gown of any type is beaucoup bucks, and considering I will only wear this thing one time (not even a chance for a repeat performance because we fully intend for this to be my last pregnancy), it just does not seem reasonable to spend over $100 on something.
I had heard of people using the site Rent the Runway with a lot of success to rent formal gowns, but they have no maternity wear.  I did manage to find a couple other sites, including the cleverly named Rent Maternity Wear, that seem to offer a similar service.  It was there that I tracked down a few possibilities:

Option 1

Option 2

Option 3

Option 4

But now I really can't decide.  I am a little wary of using this kind of service, especially without being able to try on the dress beforehand.  Plus, I'm not really ecstatic about any of the above pictures.  Like most things maternity, I feel like I'm settling and just buying something to literally have something to wear, not because it will actually look nice.

So what do you all think?  Anyone ever used a rental wear site?  Have a dress preference from the above?  Or a genius way to somehow otherwise dress a 7-month moderate sized pregnant bump?  I would love any and all help you all can give!!!

If you can't get enough of me, I'm also guest posting today over at RoCa and Company!  Go visit:)