Actually if it moves "at snails pace", you can take a series of images - say a burst of 10, for focus stacking!
Snail pace is something completely different when you're this close to it.
I wanted these frontal shots but it's hard when you have to manually focus while the snail is moving towards you. I just had a small burst of sun rays on that area and the snail gave it all she could to get out of those quickly. It was pretty fast and after not too long decided to take the route down.
The two pictures show pretty well the "enormous" DOF I have to work with while it is moving and I'm moving. Not as easy as I hoped it to be.
Focus stacking this is impossible I fear.