Any suggestions about the best technique to drill holes for this pad-eye "true" so they line up with a stainless backing plate? I don't want to risk "wandering" within the fiberglass. (see image)

There are three 5/16" (or 8mm) holes. I was thinking of starting with one hole and then using a clamp to fix the position for the second hole -- then drill the remaining two holes starting with a small bit (1/8" working up to 5/16") so the stainless would act as a "guide". Would welcome better suggestions. Would drill small pilot holes to start all.