I'm afraid this is going to be a big problem. That kit is in fact a reissue of an extremely old one, originally produced by ITC. It has a ... well, pretty dubious reputation in terms of accuracy. I think ITC had a pretty good excuse for not getting things quite right: the kit was released while the plans of the real ship were still classified. (She was built with the help of a huge government subsidy, on the understanding that, in time of war, she would be immediately turned over to the Navy for use as a high-speed troop transport.) My guess is that the kit designers worked from nothing more than photographs, which probably didn't show the davits clearly - so the davits got left off.
Revell issued its United States at about the same time. I haven't seen that kit for many years, but I'm pretty clear in my recollection that its lifeboats were molded integrally with the sides of the superstructure. If Revell represented the davits at all, they probably were pretty crude. It was on a smaller scale, though, so their absence probably wasn't as conspicuous.
Bluejacket is certainly worth a try, but I'm afraid its davits are going to be way out of scale. I'm afraid this is a case of "scratch build 'em or learn to live without 'em."
This is one more reminder of how badly represented civilian ships are in the plastic (and resin) ship model world. The U.S. is an important and beautiful ship; she deserves at least one state-of-the-art kit. But apparently the market just isn't there. A few years back, White Ensign Models proposed issuing a 1/700 R.M.S. Aquitania in resin - if a modest number of customers agreed in advance to buy it. There weren't enough takers.
Good luck.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.