for extra midi outputs you can also build something like a midi thru which is simply a hex buffer and some resistors. this will give you easily 5 extra midi outs. i assume you want 5 physical ports but you don't need to send 5 times 16 different channels, right? (the midi output would be the same on all the 5 outputs with that solution)
there are many midi thru schematics on the net. you can build a dedicated box or integrate it with the axoloti, then you can even omit the optocoupler.