Okay, this might be already covered in some capacity and may get some groans, but the question (which also probably has too many variables) is...

If things are generally normal (nothing too crazy in terms of chain stays or head tube angles or lots of other things I am sure I am missing), can you make trail as "low" as you want it/handle it?

Or maybe a better question is what is the lowest trail value you have ever built a road bike around (let's say 700x23 tires for ease of use even if we know 25< is better)?