I think you can just set the I2C pins in MyBoardNRF5.h without remapping the pins in MyBoardNRF5.cpp.
Look in MyBoardNRF5.h, under the Wire Interfaces section. Set SDL and SCA to 30 and 31 as appropriate for your board.
@monte, I've implemented in PR https://github.com/mysensors/NodeManager/pull/517 something going in the direction you pointed out. Before explaining just a simple assumption first: NodeManager is intended to run on a number of different boards, most of them with limited memory so this capability has to take this constraint into consideration (hence no json parsing, reuse of existing communication mechanism, capability disabled by default, etc.)
Apart from this, I found a sort of compromise to enable/disable sensors, even remotely and optionally persisting the status across a reboot. All the implementation details are within the PR (down below, the PR also include other enhancements) feel free to provide comments here or on Github. Hope it could be useful to avoid reimplementing the entire logic from scratch
Nice project
manufacturers datasheets, RF appnotes etc all mention this, with results for different usecases (like gnd plane size etc). I mentioned it a few times on the forum:
nothing under or near antenna (keep out zone)
their matching circuit, and CE/FCC certif are based on their development boards+their antenna if external, often without enclosure.
there are a very few pcb antennas which are resilient to untuning. ceramic or meandered pcb are usually more compact but less resilient (like when you approach your hand and device suddently has better or worst communication)
once you change any of these parameters (board shape, gnd size, enclosure etc), it breaks FCC, and may need retuning, still you can get useable range.
"ideally" tuning should be done once enclosed for example. manufacturers can't cover all cases.
on my side, I try to follow these rules. and when interested in a design or a device, I check this. Mainly the routing+gnd, antenna choice, keepout zone, and orientation vs my usecase (long range needed or not for example)