reinforcing a shaved tailgate

So now that my engine rebuild project is over I am ready to start cutting and doing the fun stuff. I have the taillight fillers, new roll pan, tailgate filler (or skin same difference), and the cadi taillights with buckets. I am going to shave the tailgate and want to reinforce it, but I don't want the rounded corners way of doing it. I keep seeing the squared off corners on shaved tailgates and want to know what reinforcing they did to stop the body welds from cracking. Thanks for any input.