xbox 360 + lcd power inverter

I am going on an 8 hour road trip soon. I always wanted a power inverter just to charge a laptop, but I thought I might as well get a nice one in case I ever want to connect my 360 to an LCD monitor in my car. Then I thought I might as well do it on the road trip, so anyone can play.

The model Xbox 360 I have says the following:
Under DC output the power brick says 175 Watts.

The LCD Monitor I would use says on the power brick that the DC Output of the monitor is 12V at 4A, so that's just a mere 48 Watts?

Adding up these two wattages, 175W for the Xbox 360 and 48W for the monitor, I get 223 Watts.

Would a 300 Watt inverter be sufficient? Or should I get a 500 Watt?

Is modified sine wave ok or will I need pure sine?

Lastly, if I did get these two running, would it be safe to have with my 300 Watt amp (which will be the audio for the Xbox) and HID's, or is that too much stress on my battery / alternator?

I'll post pics if I get this up. I planned on hard wiring the inverter to my battery and running it under the passenger seat, provided it won't be too hot, and has the clearance.

Ah...... I can't edit my post. But this is the inverter I was looking into getting. Thoughts would be appreciated.

Xantrex 400W Power Inverter

read this: https://www.mechatroniks.com/wrx/xbox360.html
It'll help solve your whole Xbox 360 install questions

-------------
You only dont know what you don't ask about

Sacred Ground C.C.

i have come to think that modified sine wave is fine for most things but when it comes to my computers a find that i have less power problems with true sine wave and the ture sine wave i think are a little better but they do cost more, and what ever you to be sure to ground the case

-------------
time is not wasted when you are wasted all the time