BRL,
The really good way to get good relevant advice is for a competent pilot/operator to discuss the specifics of your proposal with you. If you give us an idea where it is, someone from Rotorheads may well volunteer to help out................
In your own interests, there are 1 or 2 things that you should do too before allowing visiting heles. I suggest that it would be good to prepare a short note about the site for pilots that could be faxed/emailed to anyone wanting to fly-in, which would also define te terms of use of the site. You also ought to get them to undertake the landing at their own risk. The note can also be sent to one of a number of helicopter landing site guides that could help to generate you a bit of trade too.
It would be sensible to make it clear that you require prior permission before a landing (PPR). This would avoid possible untimely arrivals.