I appreciate the desire, but I can't think of a practical way to do that to an MVP. Basically, you would need to come up with some kind of heavy duty waterproof baggy, that has a seal opening big enough to get the MVP inside and secure enough to make sure no 'bad' seal happens. And then it has to have an opening - with another seal like an o-ring - that the 510 connector can pass
through - that can't be damaged by heat from the 510 and any
device you screw onto it either. I wouldn't trust me to come up with something like that that would be truly waterproof.
In the last year I have seen mention of all of one PV out there that was being advertised as waterproof - right down to having the o-ring seals between the closure parts. I'm blank on the name right now - anyone know what it is? It may have been a SmokTech thing.