If you are crushing 5/16" tube, when it's nearly done, drill a 1/4" hole through the crushed part, and then slide a washer with a 1/4" hole in so that the holes line up. Then crush it up hard and file/grind the end round to match the washer radius.
The best home made mudguard stays I've seen are Selly Oak branch Doug Walker's on his FH special. They are stainless and made so well you'd think they were factory jobs. You'd have to speak to him though...
(AOMCC Exec Committee & Selly Oak branch rep)
'47VB, '51KH, '58FH, '05 BMW oilhead boxer.