I always take the overly cautious approach on ground runs. Sturdy rope tied to the engine mount and looped around a steel fence post. If tail dragger, the rope is draped over the horizontal stabs to keep the tail down. Plus wheel chocks of course.
I bent a tie down bracket once on a non RV type homebuilt, so shy away from using them.
Good fence post, through experience I know it's good for over 450HP.
built a few RVs, rebuilt a few more, hot rodded more, & maintained/updated a big bunch more