1) Must be a suitable distance from your primary home.
2) Must be available for your year-round occupancy. (Property can be occupied by someone else so long as it's not under a timeshare arrangement.)
3) Must not enter into any rental agreements, and must maintain exclusive control over the property (no management agreements, etc.).
I think you have a gray area here, but investment is the safe way to go if you really will have someone else living there. In my mind, that makes a case that it's not suitable for YOUR occupancy. Yes, you may stay there occasionally, but someone else is LIVING there and that's the distinction.
I'm with your loan officer here and would call it a rental/investment.
Now lets assume you work in London and want to buy a house in Fremont as your head office is in San Jose. For work related reasons you have to attend meetings every other week in Fremont. This scenario will most likely qualify Fremont house as your second house. On the other hand, if you are only visiting San jose once a year and for only 30 days, underwriter will have a lot ???s to consider this as your second residence. Now if you,re flying in 30 times a year for work reason, that story will be different! But 30 times from London- that's a lot of frequent flyer miles :). All the best
Best of Luck!