I've got another possible solution to suggest:
Since you are already supplying power too the xlr/trs adapter, you could with a few resistors impedance match the different kinds of cable which will adress the problem mentioned here about reflections. However this will comes at a cost, it will lower the signal level but that could be addressed with a simple amplifier since you've got power.
Please not that this will not solve the high characteristic capacitance problem that could be that case with audio cable, that could be solved with recommending a specific cable that meets that criteria.
This way of doing it is not following the standard, but done right it would avoid all that which you want to avoid with following the standard.
Since you are already supplying power too the xlr/trs adapter, you could with a few resistors impedance match the different kinds of cable which will adress the problem mentioned here about reflections. However this will comes at a cost, it will lower the signal level but that could be addressed with a simple amplifier since you've got power.
Please not that this will not solve the high characteristic capacitance problem that could be that case with audio cable, that could be solved with recommending a specific cable that meets that criteria.
This way of doing it is not following the standard, but done right it would avoid all that which you want to avoid with following the standard.