We are having a memories wedding at Disney on Halloween day and we fully intend to wear our wedding gear at MNSSHP the same night. 
We are getting married on that day (flying over from the UK) because we are an 'alternative' couple ;-)
My fiancé's wedding suit is very 'vamp' and my dress is a traditional ivory dress (similar fit to yours) but I've had it altered with lots of black cobweb lace.
We marry at 1pm near the grand Floridian and we have dinner reservation at cinderella's castle at 4:20 then on to MNSSHP.
 It's just me, my hubby-to-be and our 2 kids.
I love the idea of hiring a locker and taking a separate lightweight costume so that we can change if we wish but I am planning on wearing my dress for as long as I can - hopefully all night.
It is our first trip to WDW, and it will probably be our last due to finances so I really want to make it as special as we can. 
We have had a totally rubbish year and this wedding and holiday of a life time have been the shining light at the end of a long dark tunnel.
We will never again get married, never again spend our favourite day of the year in Disney world and we plan to fully enjoy both experiences and tie both together and enjoy every second.
To have wonderful photo pass pictures of us enjoying ourselves (after already paying Disney a lot of money for our ceremony photoshoot) would be lovely, it's our special day and the only guests we have are 2 children so couple shots of us on our own would be impossible after the Disney wedding photographer.
I wouldnt enjoy a MK Disney photoshoot. Getting up at stupid o'clock, no kids allowed, it not even being on our wedding day etc etc I want pictures of our day as it happens, of us having fun and laughing with our kids 

We plan to have as much fun as possible and to laugh our way through the night.
When we return to the uk we are having a fancy dress reception... So if my wedding dress gets ruined at Disney then I will just alter it into a reception 'corpse bride' dress 
 
I think it is a bit unsporting to be against someone making the most of a 'loop hole' just because you didn't think to do it yourself.