Advice on hanging gymnastic rings in garage rafters?

I have ordered this metal bracket for hanging gymnastic rings in my garage to add to my home gym ( ). My garage does not have a second story above it, only the roof.

On it's own, the bracket will span 2 of my rafters and it appears many mount it directly to the rafters or joists without a stringer. However I'm likely going to mount a 2x4 or 2x6 stringer across 4 different rafters (it's a drywalled ceiling), to double down since I'll be hanging on these as will my kids. For what it's worth, I weigh about 170lbs.

I would like a gut check and any feedback on the following approach:
Cut a 2x to span 4 of the rafters Use stud finder to mark off the rafters Mark and predrill for lag screws Mount the 2x to the outermost rafters with 6'' 3/8 stainless steel lags (advice on smaller or shorter?) Mount the ring hanger bracket inthe center of the 2x with the same 6'' 3/8 stainless steel lags, this time going through the bracket, the 2x, and into the rafter Victory?
I would appreciate any feedback or help in making sure I get a very strong and secure mount for this ring hanger. I received some feedback on Reddit that this may significantly weaken the rafters that got me concerned?

#Garage #Structural