So many things to consider,
and I am not near as experienced as most others commenting in this thread. But I love Grimm Jeeper as well as
@TNBrett mentioned. You would need 4.88 gear's to match what 3.55's and wide ratio guts would do in 1st and R.
Gear swap would limit your cruising speed and hurt mpg, you mention its your daily work pickup, in my situation, the CC would be used more than the RC's or SC's (I have 4 in my family).
Based on my comparisons, and reading others' experiences/suggestions: without making a budget comparison spreadsheet; I would keep the gears, and add a turbo, manual hubs, and wide ratio guts. This is most likely time consuming and expensive vs a gear/axle swap. What about finding super duty axles with factory 4.88's/5.13's? Would they bolt in..? Is there a kit available? I just think 4.10's/4.56's would not be enough...... They always say "don't fear the gear"
Side Note:
@david85 caught my attention with his mention of 3.08's with a E4OD. I need a turbo at my elevation, and it looks like my van will stay 2wd for awhile. (Trying to afford a 30x40 garage so I can get off the dirt). So turbo addition plus 3.08's sound like a hwy cruising win for my van.
Good Luck Rock!