I'm heading back to New Hampshire for a few months this summer and would like to load a second copy of Sonar Platinum on a computer I have in New Hampshire.  Is there anything I must do with Cakewalk so as to not violate terms and conditions of my purchase?

Nope. Just install it.

Install any way you can.
 
1. Download and install CCC
or
2. Take a copy of the latest installer files if you do not plan to install any updates during that time.

You ain't supposed to use both at one time, tho. 
 
The purpose of a reg # step is so Cake will know how many machines you have loaded your copy of SONAR onto.  If they start getting multiple requests they know you (well, not you because you would never do such a thing, but someone somewhere has "sold" their copy of SONAR along with the serial # to multiple customers on the internet and Cake can stop giving away the milk free, so to speak.  You find these marks sometimes on the forums, wondering why their $20 version of several hundred $s worth of software won't work.

Thanks for the prompt and the tremendous responses!