Well ... Kinda sorta along the same lines ...
I originally got a so called 4' brush hog with my 25 HP SCUT, which actually is 4' outside to outside, cut is 44" ... after I put on 3" spacers my SCUT rear tires are 50" wide outside to outside ... I had to mow with one set of tires on the previous cut area ... Especially on a turn, as it has quite a tail swing!
I ended up the next year trading it the next year for a 5' version which has a 56" cut worked fine, but required me keeping something in the bucket for front ballast weight, as it was obviously a foot longer, and also heavier, so it was a bit light on the steering at times ...
With all that said ... I then bought another tractor, but didn't have the cash to buy a mower for it, so put the 5' brush hog behind it as I was eager to mow with my much more comfortable larger tires, and A/C ... It worked just fine! IIRC tires are 68" wide ...
My concerns were, does 3 inches narrower than tracks on back matter. I wondered if tall grass got matted down and didn’t get cut on next pass
It's just the nature of the brush hog design, you gotta run over the grass before you cut it ... My guess is that using a 4' brush hog behind a B, inorder to have a slight overlap, you will want to have one side of the tires on at least part, if not all of previous pass of cut grass ...
Do you know if your 4' brush hog actually cuts 4', or is it less like my Bush Hog Brand is?