Which gear ratio?

I have a 98 tacoma 2.7L 4x4 with a custom camper on it so its hauling around a lot of permanent weight. The diff ratio is 3.58. Starting is a pain...it lugs and is difficult to start up hill. I have to max out the rpm range of each gear to get moving...4th on the freeway gets me to 70 with no umph left! I barely use 5th as I have to be on the flat or downhill and can only go 65 on flat.
Sooo... I'm looking to swap diffs and looking for advice on what I could expect from a 4.1 vs a 4.3???

 

total miles on Ur 98

Ur aero with camper is slowing U down

gearing will help only marginally

more RPMs all the time not more power