To answer "where will you put the hidden panels in design mode" --
Make an additional six (hidden) pages per bank, pages 7-12!!
Hidden page 7 holds hidden panels for page 1
Hidden page 8 holds hidden panels for page 2, etc
These hidden pages would only be accessible in Design mode, but otherwise function normally.
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Basically by creating an additional bank of pages, you're effectively creating an additional "buffer" that can be used creatively. If I'm not mistaken (took programming classes but don't program for a living), the concept of "buffers" or "instances" historically has solved a lot of issues:
-- MMORPGs where players are spawned into zone "instances" to resolve certain common conflicts
-- synth edit buffer allows designer to tweak patch in volatile memory buffer but not destructively alter original patch in permanent storage
-- DOS and the old x86 issues of memory limitations, of apps crashing other apps, were solved by isolating programs into their own separate working space, or buffers
-- DJ Softcore that you interviewed discovered he needed a buffer of an additional 8-tracks to prep in his headphones, so he could "drop the beat" smoothly and keep the crowd dancing
Stretching the analogy to MD, having a buffer of 7-12 pages per bank might could solve some issues, as well as open new opportunities...
-- context-sensitive hidden panels that display only on certain conditions
-- "pop-up" info, like text instructions
-- label, text, and image swaps, for pseudo-dynamic pizzazz
Food for thought.