I would lock the 30 w/o much worry if your on 33's or larger just do something o keep the capsfrom spinning off the clips, either grind the shafts for full circle clips or tack weld the caps in, or I'm going to try something a little different as I don't like thos solutions for couple reasons, I'm going to try using JB-weld to tack the caps in place. I'll be letting people know how this works after I try it. I've seen people running hp30's with 35-38's lockers, in XJ/ZJ's w/ 4.0l/5.2l and they both used stock shafts for a few years then went to alloy's but they were also running some seriously hard rock trails and were tired of the 1-2 shafts a year that would break.
Also I wouldn't be so worried so much about the rear 35, for the average wheeler running 33's or less locking it isn;t a big deal, I have a few buddies running locked 35's on 33's with out any issues of breaking, thy do carry spare shafts in case there is a problem, but so far I have only been on one wheeling trip where tey were needed and that was after the axle was severly abused trying to drag another TJ, (who lost a front wheel knuckle and all) out of a water hole up hill in 2' of snow ( I know it sounds like bs, but it was a bad night.)