Walt Wright's 'checkerboarding' for swarm control leaves the entire brood chamber untouched.
The brood chamber functions best after it reaches a minimum size and is undisturbed. Splitting the brood nest will set the hive back and open the door to small hive beetles.
If you want to start a second deep for the expansion of the brood chamber, you can open the sides of the brood nest, as described by Jen, by removing the already drawn frames from just outside the brood nest in the first box and place them in your new box just over the brood nest (replacing them with frames and foundation). Sometimes I have placed an empty frame between them in the new box if there is a good honey flow, but probably not at this time of year, Florida is probably different.
If you have Small Hive Beetles, they will have more opportunity with more space. Have a tool to crush them when you inspect next visit.
Personally I'd remove the excluder for now, that would ease any pressure on the size of the brood nest. Then, after the eighth and ninth frames are drawn in the lower box, you can add the next box with the maneuver described above.
I have not read of checkerboarding to split a hive, couldn't comment on that.
HTH
