As I've said before:
Kamara + Floyd + Red Zone = Nightmare
Completely disagree (respectfully). Actually, I see what you're saying, but I think you're wrong.
In your scenario, I would just put a safety over the top on Floyd to double him, and shade my other safety either in run support or towards Kyle Rudolph. And I leave Kamara in single coverage, 'CAUSE HE CAN'T CATCH! (Or because you know that JC won't throw to him anymore because he already cost him 4 picks.)
A nightmare for defenses, like i said earlier, I G-Tate on one side and Floyd on the other. Tate doesn't have the size, but he's got the hands, the athleticism, and the want-to that means either he's getting it or nobody is.
Last year, we had this scenario and for the first 4 games it worked. Then teams started figuring out that all Haywood would call is the fade to either side, so they doubled the WR's with the safeties (cause they didn't have to worry at all about the run) and we couldn't do crap, and we never adjusted. (Helloooooo...Tight-end anyone?)
This year, I see us using the tight-ends more in the red-zone, thus opening things up for the unstoppable fade.
To your point, if Kamara develops some hands, some confidence, and some conditioning, then yes, he's a nightmare matchup. Until then, I'll take Floyd + Tate + Rudolph...