I have total 20 WW cities on different islands (max 4 per island), all full myths - it takes long weeks to build them, or I purchased some with gold during events.
I only enter VM when it is really necessary, handoff cities when I don't want to play any longer, but I stick it out until all important cities can be taken by players who would handle them with resonsibility... or I like to think, I'm that type of player.
So I have to kill full myth nukes, give up cities for a few days VM even or face the consequences, my alliance will have to defend my wonder cities blindly, like if I was on an attackable ban although I had to attend to a funeral of a family member for example in another state...
Probably when I return, they won't see in me the loyal player who I used to be, but someone who didn't help to handoff cities, lost their wonder, however it was a family emergency.
All players deserve vacation without loss of cities, units. Implement a shorter time limit of VM on wonders, or a maximum share of WW cities per player / island, but don't discriminate your customers who would not abuse VM as strategy!