At the risk of being redundant, or telling you stuff you already know, let me share some thoughts.
The C 1000, if you bought it new, should have a super cardioid attachment for the diaphragm that gives it a similar pickup pattern to the OM5. If you haven't tried it, do so. I think the newer ones also have a bass roll off switch.
Experiment with the different settings on the B2, as well as positioning. If putting the L1s off to the side means having the B2 near, or against, a wall use the setting of least bass output.
In the early years, after introduction of the L1 series of systems, there was quite a bit of conversation about how to use them with traditional Bluegrass bands gathered around a single large diaphragm mic. I don't recall anyone being successful with the L1 behind the performers, or with loud volume.
I know that Ear Trumpet makes a lot of claims about their mics ability to perform without feedback issues. I see them used by a lot of artists with conventional equipment to a very high degree of success. I have been intrigued, and curious about how they might work for me, but have so far not taken the bait on another expensive mic that might go unused. That being said, I would not take their word as gospel on the use of presets. The vocal presets are tailored to give good vocal sound and eliminate some problem, or unnecessary, frequencies. Bluegrass musicians have for a very long time played their instruments through mics EQed for vocals. At least give presets a try.
Keep us informed of your successes/failures with this system and your band. You have the potential of answering a lot of questions for us, rather than us answering for you.