My brother and I own adjacent waterfront lots on a highly developed lake. Our street is next to a fancy country club neighborhood, with a golf course & yacht club. We aren't in the HOA, which is a bonus to many buyers. Our 2 lots are large enough to subdivide, creating a 3rd lot. At first, we thought selling it as 3 lots would be the most profitable way to go. But we have reconsidered that and feel we might do better offering both lots together, selling it as one very large lot (almost 2 acres). Three separate lots are only worth what the market will bear for an individual lot, and some others may have better features (better view, deeper water, etc.) than ours. But nobody has a 2-acre lot available on the lake. Recently a few ultra-wealthy people have combined lots to build extremely large homes nearby. One is 35,000 sf and another on the next street from us is 24,000 sf.

Neither sits on as large a lot as ours, but both have better views.

Since we can sell it as 3 lots we feel like the large lot is worth more than the total that we could reasonably expect to get from selling them separately, because 3 individual lots cannot be combined to create a larger parcel unless they are adjacent.  Assuming our reasoning is correct, how much of a premium should we ask?  What is the risk of asking too much?  

Can we say we are entertaining offers starting at "X" for a certain time frame (90-120 days or so) and require a percentage of the offer for a deposit.  Would 5% be reasonable?  Would this be the best way to maximize the selling price, without actually asking an outrageous price?

We aren't planning to list with an agent.  We plan to have a RE attorney handle the transaction.  

Any advice or suggestions will be appreciated.