You should be able to build most road frames so that the bars are level with the seat, or at least close enough. The wheelbase isn't a concern when it comes to weight distribution. Touring frames' longer chainstays help with stability when loaded, yes, but they also move panniers farther away to eliminate heel strike.

Then there's the other extreme -- going a lot lower for more comfort. There was another BF'er who, after consulting with his shop, eventually dropped his bars pretty low after trying to raise them in search of a comfortable position. What he noticed was that his core muscles started carrying the weight of his torso, reducing the weight felt by his arms. It also took the load off of his shoulders, so his upper back and neck weren't drooping between his shoulders -- which also reduced the pain he was feeling in his neck.