Since no one answered, I'll put my ugly hack below - it's not polished but it works and is fast to use.
I set up an alias in my `~/.bash_profile` that creates and calls a function that takes the number of splits as an argument.
`alias splitpanes='_splitpanes() { for i in $(seq "$1"); do tmux lsp -F "#{pane_index}" | tac | xargs -I{} tmux split-pane -t {} $(if [ $(($i%2)) -eq 0 ]; then echo "-h"; fi;); done; }; _splitpanes'`
With the modulo 2 check half of the times it splits it horizontally, so that in the end you end up with `2 ^ splits` evenly-sized panes.
Now I can e.g. call `splitpanes 6` and end up with 64 panes (after a few seconds of rendering).