The reeds, etc are great and especially, so is the oxygen you incorporate with digging. The stink is anaerobic decomp smell.....decomp without oxygen. The oxygen you are adding will change the decomp to aerobic which doesn't smell.
Is the threat from moisture over?? Or will more moisture back up into the area? If water will move back in or if the water table is so high underneath the ground won't drain.......your garden efforts are going to be difficult to say the least.
As the reeds, etc disappear, you'll need to incorporate compost regularly or else the sand will reign....but sand is inert. Regular incorporation of compost is the best solution.......it provides needed cation (cat-ion) locations that the sand can't provide to hold nutrients and as the soil dries and the sand predominates, it keeps moisture in the soil.......something hard to imagine now.
