there is a reason why most bikes are 73 degree with 45-55mm rake. It is the sweet spot. Low trail road bikes usually have 73 degree head tubes too. I don't think you want a tri geometry on a road bike. Those bikes are really pretty unstable with the intent that they aren't going to be ridden in packs or on twisty roads. You can get most of the benefit without the forward seat tube angle. Just swap seat posts and add clip on aero bars. For most people, just adding the bars is more than enough.

If you want to play with geometry, there is a web version of bikecad. Also, there is a freeware program called rattlecad. Not sure if either one of those will do toe overlap, the paid version of bikecad does. I really don't care much about toe overlap on my bikes. I think most people that race can handle a toe overlap situation when it happens once every 5 years