Tips on Buying Cars: Trading in with negative equity, used, car

Question
I have read several posts and am trying to understand how I can get the best deal on my trade in value, and a new loan.  We are looking for a used truck and want to trade in our current vehicle.  We owe about $15K on it, and trade in value is $11.5K, so we know that we have about $3500 negative in it.  If we are able to secure a price for our used car at above wholesale, or lower than retail KBB price, would that help us in utilizing our new loan with the negative value of our trade?  I know other options are coming up with a bigger down payment, or just simply rolling it over, but I'd like to walk away in the drivers seat, both in the car and with the loan.  
One dealer that we recently visited, had a KBB retail price of 19,041 on his car and would not budge on their asking price of 21,988.  After reading several articles today, I see that their wholesale is about 13,400 (using trade in value of that truck).  They simply kept stating that they would only profit about $900 on this truck and therefore couldn't reduce the price.  
So, I would like to know how to best negotiate all the steps necessary for getting the best deal.  (trade in value and selling price of the new vehicle)
Thank you for your assistance

Answer
Hi Cindy,

The big issue here is how much will be the true negative factor, I like to help you but need some answers before I can guide you with some options.

1,,, Phone the lender and get a pay out amount,,, which is ?
2,,, I need info on your current vehicle to arrive at what I consider market value.
3,,, The dealer you recently visited, is there a link I can view this vehicle.

The ideal win win is to have a buyer lined up that you bring along whom will purchase your trade from the dealer where your buying your new vehicle,,, you benefit 2 ways, with taxes and having maximized your trade.

This thread is public, if you want to continue I suggest you e-mail me at paulsenray@yahoo.com
If you have not already been on my website I would like for you to visit this link http://usedcartips.org/TRDE.html most may not apply to your situation but you will pick up a few pointers.

Ray  
http://www.usedcartips.org/