... I'm a little confused on your point for the turn signal input. Wouldn't the input be a (+) coming from the m.unit paralleled from either of the turn signal outputs?
There are two inputs (lights) supplied for individual left & right lamps, with a common negative
Yes, you can use diodes from the two outputs to steer to just one of those lamps leaving one available for other options
But the one that is unused will require a (+) input - that logic is fixed as far as the tun lamps go.
It will also be 'green' which is not ideal as a 'warning' lamp but that is relatively minor nit.
The high beam can be either polarity but of course would be (+)
The Neutral and 'Other' can also be either polarity and you would likely want both of these as (-)
Oh, to follow up on your point for the neutral indicator. Will that require one of RBM's boards or is there a simpler way?
There are three signals from the GPS - those are all three (-) - i.e. connected to ground - when in neutral;
for other gears at least one of them is 'open' (pulled high as required externally)
You will find a few options in the forums - the most common is the use of multiple relays which is a bit 'clunky'
@RBM's board obviously does a lot more than just that function - you might ask him if he would be able to send you a stripped-down version with just the neutral decode chip.
Or with his kind permission DIY & use the part of the circuit that does that function on a mini-board