I have a 2000 Impala. i calculated the approximate weight of the trunk lid and it's heavy. If you replace the trunk lift support struts, the truck gets much much lighter. I made some thickness measurements and estimated the area and used the density of steel to come up with a value. I think it was between 50 and 100 lbs.
I did that because I wanted to estimate the weight when I replaced the support struts. I didn't have a helper.
The manufacturer of the replacements liked my replacement technique. I bought some 1/2"d rope by the foot at Home Depot. The trunk already had a eye bolt installed long ago to make it easier to tie down the lid. it's located in the center by the trunk latch. You can't buy rope by the foot anymore at HD because of somebody making nooses by the rope area.
The rope has to fit through the rear windows and attach to the trunk at my eye bolt with about 6-10" below fully up.
This then holds your trunk lid up without a helper very safely.
I used a spring removal tool to remove the clips because it's awkward otherwise. You have the 6 inches or so to help you put them back on.
The aftermarket manufacturer gave me the numbers for the maximum force and he said that the force is dependent on the angle of the strut.
I think it was about $20.00 of rope and $15.00 in the spring removal tool. Time was minimal.
if I also remember, I took a scale and measured the force to open the lid. I think it was no more than about 10lbs.