mobile home block wireless router signals?

Okay, so when we are going to get some money in May, my Mom is gonna buy a laptop and a wireless router, replacing our current wired one.
Now, we live in a trailer for Financial Reasons.(We own it, property tax ALOT cheaper than a house, we can alter it,etc.3 bed 2 bath) but the outside of the trailer being metal...how well would it block our wireless waves from being used by outsiders? Yes, there are windows, but the metal would provide SOME shielding, right?
Yes,I'm going to secure it, but I'm curious about this.

Your metal skinned trailer will only block the signal if the thickness of the blocking material is greater than the wavelength

lets see:
2.4GHz signals have a wavelength of approx. 120mm

16 gauge sheet metal has a thickness approx. 1.5mm

Q.E.D.: No dice

Turning the broadcast power down is a better bet since the signal strength falls off at distance per the inverse square law

Ah, Thank you much!
Well I guess if I wanna WoWfag outside I can Hijack mom's laptop then...This thing gets hot in the summer, even with 2 air units. Also: NOBODY INSTALLS CENTRAL IN TRAILERS. none that we can find. -.-