I never tried using OTS/SU with the LM, but cant see how it wont work. Because its a compression hanger, it may be more uncomfortable compared to vacuum hangers, that's what I found.
Being honest with you, forget about the septum, dont worry about hitting it specifically, because with stretching OTS or SU, you will hit the septum anyway, and its so difficult to so call isolate it, as you know, the thing runs deep.
Just wear down, fatigue within reason through something like pumping using light vacuum i.e 3-5HG over many sets lasting no longer then 10 mins, using stretching in between, and then get into the hanger targeting the external penis you see .... that part of the tuincae, because it has no option to stretch with time, keep hitting it, the stress, the body adapts to that with growth eventually.