Static Drop Questions

[afcamaro]

I have been searching high and low and cannot figure out a direct answer. I have a few questions. I have a 70 SWB truck and want to lower it.

In the summer Im always pulling a trailer and do not want to bottom out. I want it the lowest I can go, without bottoming out. I was thinking a 3/4 drop or 4/5 drop. Id even do a 2/3 drop if I had to. Which one would be the best route to go since I will be towing?

What all would be needed for a 3/4 drop, 2/3, and 4/5 drop. I keep reading people are c-nothing at 5 and 6" drops in the rear and that is not something I want to do at this point. Do the shocks really need the relocation brackets and an adjustable panhard bar?

What is the lowest I should go with just ordering a spring in front instead of a drop spindle?

Most likely it will have 20" wheels but the 18" are not out of the question.
Any pictures would help greatly. Thanks.