Like most jobs I use bar 1 and 2 for most stuff. bar 3 is for LB, sprint and really rare stuff. If you can't learn to use two bar sets you will be a bad tank... period. Macros in this game are terrible is most cases. All jobs use at least crossbar 1 and part of the second crossbar... some require even more than that.

I personally hate the extended bars so I just switch between the bars with r1+barbutton. I am so used to it now that I amaze myself how fast I switch between the two bars without messing anything up.