I am glad that you posted on our answer forum and I would be than happy to help. The box that I think you should get is the Slingbox Pro HD the reason I am suggesting this unit for you and not the Pro is because the Pro is not compatible with the Slingbox Pro. The Pro HD is the only Slingbox supported by the iPad that has a coaxial input. So this device is the only device that would let you not interrupt the TV at your sons house and still watch the Slingbox over your iPad.
I hope this helps,
Sling Moderation Team