Thanks. I was thinking I might just go all the way though the wall
(drywall and all) and just have long bolts going through with big nuts
& washers on the inside of the garage (drywall side). That way there'd
be no chance of the fasteners pulling out.

I think the load on the fasteners will not be high except for maybe in
the winter when there's ice & snow built up... I figure if the current
trellis can support that w/o collapsing maybe my idea is overkill...

Thanks for any more feedback...

Kevin