At the risk of sounding like I know what I'm talking about....
There's a difference between vacant and unoccupied. You should read your policy and see if it has a "vacancy" exclusion/limitation or if it has a "vacant/unoccupied" exclusion/limitation.
Vacant means it's empty. Nothing there.
Unoccupied means there's all the "stuff" needed to run a household (generally means a bed, bedding, dishes, utensils) but YOU aren't there for an extended period of time.
(However, if your home is "unoccupied" but you have made somewhere else your permanent mailing address, then you have probably kicked you house back into vacant status. )
While many insurance policies read similarly, many companies add their own exclusions, nearly every company interprets things their own way, state laws can vary significantly and insurance is regulated at the state level, so there's 50 different sets of rules out there for the way insurance works.
Which is all a long-winded way of saying pretty much no one can tell you how YOUR policy is going to respond, except your agent and/or company. If they tell you something, get it in writing - because there's no guarantee that the claims dept sees things the same way.
Secondary homes and vacant homes are rated at a MUCH higher cost per thousand of coverage, so it pays to have the home classified as a primary dwelling -- but if the claim is going to be denied - you haven't saved anything.