I'm not an expert carpenter, but seeing nails into the end grain really irks me. You know it's going to fail.
I'm just letting the metal (26 ga) hang off about 9". I extended the purlins about 8" and will leave them open. <Rant> Here's framing today. I pre-cut pressure-treated purlins, short and long, for the ends that'll be exposed, so the purlin joints would be staggered. 3 - 16'ers plus one short and one long would make my 60' length plus overhang. So I get back, and they've used all short pieces on one end and all the joints are lined up
. It gets worse. Later, I notice that, instead of using the long pieces on the other end, they cut 4' off those pieces and then used 4' pieces of untreated to make up the length. So I have a nice stack of 4' long PT scrap and 4 or 5 16' 2x4s wasted. All to get a substandard (and overpriced) job.
<Rant off>