How to carry high current on PCB

I haven't seen anybody else mention temperature.

Perhaps you left the default 10 degree rise in the online calculator?

That's pretty conservative. A 20 degree rise isn't that bad in a lot of situations.

And if you aren't running the highest current continuously, it's quite possible even a higher temp rise would be acceptable, since it will have time to cool down between cycles.

High-current PCB bus bars are available from several suppliers, such as:

http://www.espbus.com

and are an ideal solution. A quick search for "PCB bus bars" will yield a number of suppliers.

The first answer would be to specify thicker copper than the default, which is usually "1 ounce". 2 ounce copper isn't usually that much more money. After that it gets expensive. There is also a limit on how far board houses can go with this. The thickest I've ever heard of is 5 ounce copper.

If this is a one off or low quantity, then leaving the solder mask off the trace and soldering a wire over it is a legitimate thing to do. A #10 copper wire can carry way more current than even a thick PCB trace of reasonable width. Consider how the current has to get onto and off the extra copper wire though. It's easy to solve the bulk conduction problem and forget about the feed points.