Are they indeterminate varieties? If not then I wouldn't worry about increasing the cages as the plants will soon max out if they haven't already. If so then you can always let them drape back down the outside of the cages as most of us do.

Don't know how tall the Burpee cages are to begin with - 42" or so? If so then 84" (7') of cage copes well with any variety as long as the whole container doesn't fall over and it sounds as if you have addressed that already.

Dave

I do, but I wont bother as it will probably not mesh with your design asethic and perfectly spaced veggie and flower pots.