This should be totally doable. You would want a body type 1 human female smuggler gunslinger.
Saboteur spec is what you want because you have regular grenades and Thermal (fire) grenades that make a big AOE explosion and fire. There are many types of Mandalorian armor some are kinda cheap on the GTN and some are really not cheap. This website should be able to help you with that https://torf.mmo-fashion.com/mandalorian-hunter/.

For Sabine's hair there are many types of hair styles in game and lots of colors. You might have to buy some color and hairstyle unlocks to get the color and style you are looking for but they can be found in the cartel market or maybe on GTN. I'm pretty sure the name Sabine has been taken by someone cause of it's popularity so be ready to get creative with spelling or accent marks.

Good luck on this project of yours.