Oh, the poor things!
I'm sure you'll be glad I tell you this- snails and slugs LOVE the dead remains of their friends, and squishing them in your garden only attracts more.
Instead, try laying a wood or plastic board at an angle, so they stick to it's underside for shade during the warm day. Then you can peel them off and let them out away from your garden.
Also, if your veggie garden is being destroyed, and it's only a patch, try putting strips of sandpaper around it- they hate crawling against that.
Hope I helped! :3