They've worked fine for 4-1/2 years as is, no sign of any spreading!Those look nice grnspot and I'm not trying to nit-pick on anything here. But, if it was mine, I'd recommend adding an additional piece of angle to box it from top to front edge of the hook. That'll effectively double your thickness and should help a lot. I'd just be afraid that will eventually spread open resulting in a potential accident. Rest of it looks awesome though. I'd like to have a boom myself but I'm getting a cherry picker next weekend.
Word to the wise fellas, the pins Deere sells are made of a medium carbon steel. This material is prone to weld cracking without proper pre and post weld treatment. I can't understand why they use it for these pins, and worse, sell them openly to the public. This isn't weekend warrior stuff.John Deere does. Part #3 ($14) and #4 ($20) below.