Driver is made for 1S4P (well, 1S; doesn’t really care about how many in parallel).

Stacking in taller tubes implies 2S or more, which’d likely pop the stock drivers.

Or use a carrier that fidgets with the arrangement to put the cells in parallel (big-ass conductors through the center, insulated platform in the middle separating the 2 stacks, etc.).

And do with within the confines of the stock tube’s width.