The first person arms (or lack of) are a real problem when dealing with the default assets.
Some campaign mods I will:
-Remove the arms/make them invisible
-Swap the shader/texture to something closer
-Play mostly in third person
Here is a good combo that works and looks nice, take the Master Chief, then swap his biped's shaders (first and third) to that of the ODST. You get a cool looking MC ODST. As seen here:
[BBvideo 800,490:30x6irae]https://youtu.be/9b21I-HSRqY[/BBvideo]
Another tag edit that works sometimes is take the MC and set his biped's shader to the MP Elite's. His hands are orange fire, he looks very cool. I also mess with the visor, setting it to black or steel.
Campaign is tricky because its so dependent on what character is set to the main player (MC or Arbiter) and it will limit what first person body parts are included in that resource map.
You can play as flood but some of the controls might be iffy, I suggest you start with 07b_forerunnership because it has a decent variety of characters, as seen here:
[BBvideo 800,490:30x6irae]https://youtu.be/u91XjQHBQ0I[/BBvideo]