monthly bookings in the low season? How much to discount?

[MoonFish]

We are based in the Caribbean, out of the hurricane belt so we have generally quite nice weather but a huge drop in guests because they can holiday near to home and enjoy similar weather.

The entire island runs dry of visitors for long stretches during this time, so I am considering offering monthly rates for the shoulder and summer months (in addition to the weekly/nightly rates) in order to attract guests, but how much do I discount? I might bring in very little across the entire period May to end of November, generally less than we make during a full week in the winter with both villas and the apartment booked solidly.

I don't want to attract people who will disrespect the property, which seems to happen each time I discount, so advice is welcome. Also, there is no washing machine in the villas, so I was considering including 2 loads of laundry a week and a morning housekeeping visit along with the weekly linen change? We generally don't do laundry or housekeeping at all, unless it's a family with kids/they've been somewhere else first (like sailing) or a preganant lady, or if guests is staying 3 weeks or longer I'll do some laundry, but no housekeeping.

I also do not want to attract local residents/expats/etc who will want to bring all their friends over to hang by the pool all day and use the bathroom as we are on a beach with limited toilet facilities. I don't want to sit around playing Mrs Meany blocking guests at the gate, and my insurance company would be very unhappy!

Advice appreciated!