I am glad to see that you have the opportunity to change around things. Did they really give you the Green Light to re arrange? Unless what you want is agreed to before anyone else makes changes then all bets are off when you arrive that day. Needless to say all the time taken to give you suggestions would be wasted. You may find that the Cake or other table may be right where to want to place one of your speakers.
My contribution of Gear and Speaker placement is now limited to the given facts. You did not give the dimensions of the Floor Plan, Size of Room, Size of Dance Floor, the width of the front of the Riser on which the Head Table would reside and the location of the Doors/Entries. Where is the Cake table going to be? That would have given me the information to know what size type of system to use. If you are limited to one system then I understand you would have to work with what you have.
With that being said, based on only what you have provided I would put my speakers where your arrows are and one Satellite speaker either in the Bottom Right Corner angled towards the Dance Floor,
or about 1/5 the distance from that Corner to the Bar Corner as high up as possible . That speaker would have to have a summed stereo or Mono feed (Not a Left Side or Right Side only). If you have a Live Mixer with a Mono send, that is the signal I would use. Your DJ Table can be either where it shows it in this Diagram or Next to the Speaker between said speaker and bar. This will depend on your available length of Speaker/Signal Cabling. Watch how you angle your speakers, you don't want them firing across each other or firing from behind one another.
Caution, tripods alone on a small dance floor is a recipe for being bumped and toppled. To protect the legs, I would put a sub in front of each one or pole mount the tops on top of the Subs.
It would be nice that whatever option you choose, that you take pictures of the different angles of the room, not just want you want us to see, before the Guests arrive and share those pics with us after the event. Good Luck with it.
PS. I like Bob's idea about the wedges but I would use them on each end on top of the riser. Again we don't know the length because you did not provide it.