Anyone can be a trustee, you dont need to live in the block or have anything to do it.
I don't think there is a limit to one trustee per unit, there is however a limit of one vote per unit.
So you or your girlfriend (whoever is the owner) has one vote for a trustee.
A way around this would be to get a proxy from other owners and be their representative. You then have their vote and the ability vote a second time.
I remember however that there is a limit to the amount of proxies one can get / receive.
Best would be to review the sectional title act on the above, I wouldn’t take the above as concrete as my memory is a bit hazy