I've been to the last two wikimanias, plus GLAM wiki here in London and several conferences in my real life. I absolutely agree with the argument that the lifecycle of a volunteer is too short to have 24 month gaps between wikimanias. But there are sensible things that could be done to simplify the process.
1 Don't reinvent all the wheels. The local team has to find venues and accommodation, but do they really need to create their own booking system from scratch (I think this is one area where Poland came unstuck).
2 Recruit freely. Once you know who has the bid then a call for volunteers can't hurt and can be last minute. Yes it is nice to involve the local chapter, but if the local chapter is short of people to do particular things then why not ask for a few regulars to urn up a few days early or late and do the tasks you haven't otherwise managed.
3 Use a resort town that is used to hosting conferences - ideally one that will supply some of the logistical support. (in the UK out of season resorts can be quite cooperative).
WereSpielChequers