RE: phoenix decathlon
Oh yeah, I wasn't kidding about those plugs being almost drilled out to worthlessness. Check the depth of the countersinking.
I found a hardwood dowel that fit exactly. Cut some slices off to fill the missing wood.
Then, since I have Forstner bits, and am always figuring ways to do things better, pulled out a larger dowel. Countersunk a larger diameter hole down to the remaining support dowels. The hole was to fit my larger dowel. Cut slices of the larger dowel to fill the new wider hole and epoxied them in. Turned the wing over and used the old holes to go through the new plugs and it was good to go. It wasn't good to go from the mfg.
We always need to study ARFs. Their design often is excellent. But their workmanship very often needs some fixing.