There is more internal foam toward the sides than at the front end of the Movos, which is why leaving some space at the end by not inserting the microphone all the way is good practice for and end-address microphone. Not sure if that will effect a side-address microphone or by how much, but it will be safest to leave some space at the end in that case as well. Aren't the Vs a bit longer than the end address capsules? The WST80 is the currently-available next size up from WST50 and likely your best bet, but you may be able to get away with a fully inserted side address capsule into WST50.
Dactylus, have the WST50's worked well with your V's?
Last recording outing I crammed a side-address Naiant X8 fig-8 + miniature DPA 4098 mid/Side pair into a WST50, but it was not really long enough. With the mid/side pair capsules correctly aligned, the rubber cuff at the back of the Movo extended a bit past the side-address openings of the fig-8, so I ended up rigging up a little wire thing to put tension on the cuff and pull back either side just enough to make sure there was no indirect occlusion out to either side. That wouldn't be necessary with WST80, but I was trying for minimal size and had WST50 in the other mic positions. Worked well in that regard, however there wasn't enough wind to really test the effectiveness of the wind-screening.