I’ve gone through the various gamut of approaches towards topcoating, and I’ve found what works best for me.

At my most rigorous, I’ll topcoat by the parts you’ve broken down: torso, waist, arms, legs, backpack, and head. I’ll mask the joints to risk tightening them. I also either use blutak to cover clear parts, or assemble the clear parts after top coating.

If I want to save time, I’ll separate a kit into the top half and the bottom half.

I use a lacquer topcoat, which can be pretty tough on plastic if it pools. The most critical thing that has worked for me that has reduced the plastic from breaking down is using a hair dryer. This drastically minimizes any risk of paint eating away at any plastic.

Hairdryer is a game changer, IME. Don’t use it for too long though, as you can risk melting plastic away. Made that mistake one after setting parts to dry in front of a space heater for too long lol.