the correct format is 48.8364 lat, -121.3422 long. Your current format for lat/long is degrees/minutes/seconds.
After climbing Challenger in the mid-80's, my partner & I dropped down into Luna Cirque, SE of the summit. What must be a lake during spring runoff was warm, deep, soft sand. We needed our ice axes to stake the tent, but what a joy to bare feet after days of trail, bushwhack, glacier, and sharp rock!
Then we climbed out to the South to Luna peak & ridge.
The normal route, up the Challenger Glacier, has an easy exit to 3rd class, short scramble to a single pitch, 5.6 rock climb to summit, bombproof and quite climbable in boots. There are sufficient pitons so that all you need is slings and biners and a 30m rope, but it wouldn't hurt to bring a few small pieces to sew it up. We did the Wiley Ridge approach in 2004, well described by others in a report you can see from a link called "Challenger" at the bottom of the Mount Fury page. Eiley Lake was a nice camp that we used nights 2 and 3, Beaver Pass (permit required) was a good camp for nights 1 and 4. As with all approaches to the Pickets, Devil's club and heinous brush abounds, be prepared to dry tool in dirty, cliffy areas, and wear clothes you don't mind shredding in the brush thrash. Your party should research both Beckey and Potterfield/Nelson, and have excellent map and compass skills to have a fighting chance in the Pickets.