New home construction financing

I have purchased several homes and undeveloped land over the years, but we are now getting ready to start construction on a new home and I have no experience with new home financing. We have purchased the land, and although we put 25% down, with the drop in realestate values, we have little equity. We have saved enough for about 50% of the construction but only the equivalent of about 35% of the combined house and property. We own our current home mortgage-free and the cash from the eventual sale will add another 35%. What are the best options for structuring the mortgage on the new construction given we will probably need to stay in our current home for about a year post.