Perhaps you should approach it in reverse....begin staying at the property and get to know employees. (As they get to know you, it is possible that you could get extra bennies...upgraded room or suite, etc) Once you have proven yourself a regular, you may find it easier to negotiate a discount rate.

You are considering a property with pretty high sell out rates...and 40 isn't a huge amount of nights when spread over 6 months. If the hotel can sell those nights at full price, it may not be worth it to them to consider a discount for what is in actuality less than 2 nights per week. However, once you have established yourself, 40 nights of regular income may appeal more to the front office or GM.