The TSA security people won't bat an eye at a large camera. I've carried lots of large cameras through security. They'd be much more interested if it had a large battery pack because the the bad guys have a history of building bombs to look like laptop batteries.
I used to get film hand checked, but that turned out to be more of a hassle than it was worth. They often want to "sniff" each individual roll, just to piss me off. I let them scan it now. I've never had a problem with 400 speed film that has been scanned multiple times. 120 film is also readily available in every large city in the US if you want to buy some here.
I hope you have a fun trip. The US is a large, diverse country. Kansas is nothing at all like New York, which is nothing at all like Florida, and so on. Enjoy.