Presumably the bumper is mounted directly to the frame. So long as there aren't things like rubber bushings isolating the bumper from the frame - i.e., if it bolts directly to the frame - you're good. No straps should be necessary.

 

Thanks Bob

 

I run a set up almost the same as you... as pictured your anteanna won't be grounded good enough. You need to run a wire from the lower part of that antenna stud to the chasis. I ran a cable from there to the sub wooofer bolt and it works okay, It's a compromise but I only use my CB on the trail.

It is many times better with the ground wire than without it.