5v current sourcing (another one)

I'm using a 12v PSU in my project to power various lights, LED strips, and an amplifier. I want to use it to power the Uno controlling everything, and I know it can handle it. But the problem is I'm also trying to power 3 different modules of the 5v pin of the Uno with a total current draw of about 210mA at peak.

I've noticed that the 5v regulator on the Uno gets extremely hot. I've read that the limit isn't really the amperage on the regulator, it's more the voltage drop and heat dissipation. The site linked below seems to suggest that the regulator can handle taking in 12v, and sourcing around 238mA before it shuts itself down.

http://www.thebox.myzen.co.uk/Tutorial/Power_Examples.html

My question is this: Am I able to use only the 12v PSU in this project without worrying about the 5v regulator shutting down periodically? Or should I add a DC-DC converter to power the external modules? I'd really like to keep costs and parts to a minimum for the enclosure I'm using.

The best input for the onboard regulator would be about 7 volts. 12 volts will produce more heat. You can reduce the 12 volts to about 7 volts several ways. If you want inexpensive, and have about 7 diodes, you could put then in series on that 12 volt line. Regulator cools down fast.