So, the feedback was overwhelming that a Thief class is needed for the initial 4 pages of Swords & Wizardry: Light. Of course, part of the issue is simplification and part of it is space concerns. That damn skill chart takes up some major page space.
With the input of some of the regulars during last night's Tavern Chat, I think we have a playable and elegant solution.
Climb Walls will convert to a 5 in 6 chance. All other skills will roll into on singular "Thieve's Skills Package". Chance of success is 1 in 6 at 1st level, 2 in 6 at 3rd level, 3 in 6 at 5th level, 4 in 6 at 7th level at 5 in 6 at 9th level. At 12th level, the chance for all thief abilities would be 6 in 6 - if you roll a 6, roll again and if another 6 comes up, you failed.
You could house rule the following:
All thieve's skills take 1 minute to perform. If you devote 10 minutes to the activity, you increase your chance of success by 1 in 6. If you rush and devote only 10 seconds to the task, your chance of success is lowered by 1 in 6.