You may want to screw the bar ends in maybe two turns so that only around 3/8" of thread is exposed, that is a good starting point.
Those axle brackets should definitely have gussets installed to keep them from flexing, if RPM is copying those and selling them he should at least do them right. We put the gussets on the short versions also.
Once you get the frame brackets installed take a look at the gusset system in the photo attached, it will help to strengthen that double bracket and help take the load off the bolts holding the radius rods to the frame.
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