Yeah, you can just do the rears. Not a problem.

 

Hi, Seems like you have some solid advice already. I've found a method that works great for me. To start you should always bleed brakes farthest from the master first. That would be the right rear wheel, then the left rear, right front and then left front. Also if you are having problem with the rears only now. You can just crack the right rear bleeder and gravity should take over. When fluid hits the bleeder close it and then pump and hold as usual. I gravity bleed anytime I do brakes. Hope this helps