Well, for many years I've worn underwear to hold wobbly bits in. If you feel you really must go down this route, Spanx make footless tights and shapeware shorts. These will allow you to show off your pedicure in sunny July. I'd go for light control in nude colour, it won't cause bulges around the edges (so to speak), won't show through and will be cooler. I'd also avoid anything high waisted too, they can roll down, just aim for a smooth outline rather than tummy tucks. Whatever you choose to wear underneath, be cool and comfortable, make sure going to the loo isn't a contortionist's nightmare!
However, it's your wedding, everyone will be looking at your happy face not your perfectly proportioned hour-glass figure. You can detract from your tummy in the way you hold your flowers too. Enjoy your day, relax and look back on it with pleasure. Congratulations.