Rear Suspension upgrading for GS400 E

[HAMMERHT]

Hey guys I have a question about upgrading my rear shocks.
I remember reading a while ago that Progressive shocks are good but there was a certain model for my GS400 E.

What do you guys suggest for my bike?
I'm not looking for performance necessarily. I am starting to take passengers and go for long trips with bags and I am looking for a stiffer but still comfortable setup.

Additional info,
I weigh 180 lbs (I'm working on getting at 160 lbs, if that makes a difference)
I have soft saddle bags and I like to go to Kelowna, BC (Which is one of many Canada's winery locations) and I tend to bring lots of wine back which can get very heavy.
I've limited my passengers to weigh no more than 150-165 lbs, any heavier and the bike will bottom out over bumps.

Or should I get my rear shocks rebuilt?

[LAB3]

If it's any help my 82 450t with original shocks and springs hauls me,190lbs and anothet 75lbs total between my tools and gear. Have had a passenger that weighs about 150 on it, the suspension was fine but we certainly weren't getting anywhere quick.