Not sure I’m getting my head around this, but do you need to turn off/on after each individual note or after the batch?
General rule is if you’re ever needing to do anything to change an event before it maps (eg. Transform to a CC/ Rescale to represent the range of modulation you want) you will (currently) need to use a physical loopback.
This is linked to your last question; mappings are (currently) always set up by a MIDI learn approach (so if you need to physical loopback, you will need to set (or reset) mappings by temporarily hooking up direct line in to set them via an external controller before reverting to the loopback to update the mappings by processed events returning to the physical loop in).
If you look at the patches posted today in PC to CC question, the loopback there is used to allow settings to be changed after the current event has passed through.
In the patch referred to here – Saw Returns to First Value on One-Shot! – I was using a loopback to process a mapping value created at the end of a One-Shot LFO cycle. This sort of idea could be used to bring a time element into your switching.
I must say, this notion of using mappings to switch off pipes sounds interesting for your aims. At this stage in the evening, I’m not seeing immediately what would switch them back on again…