I tested this a while ago, and it is perfectly possible to gain full influence with Mandalore while supporting the Queen. You just have to do things carefully.
Who you support seems to be decided by whether you support Vaklu or the Queen in the first riot scene. So - don't choose "the queen should listen to the will of her people".
After that, you can do what you like - choose to help Ando, to gain INF, (BUT if you want to stay roleplaying LS, you don;'t actually have to complete her quest, just say you will) and support the second riot to gain Vaklu's attention - +INF. Since in this scenario, you can also kill Vaklu for INF with Mandy, it actually works out to give you more INF than supporting Vaklu!
It worked for me, anyway.
BG.