I prefer to just get comfy wherever possible (lay-z-boy, computer chair, in bed even) and use a tray to catch trimmings.
I use a tray meant for eating a larger breakfast on--it offers enough area to catch everything.
I find the biggest thing with trimming is to move around, change position.
Doctors orders are (seriously) 10 minutes out of each hour up and moving. This isn't just comfort it's health.
You feeling like shit is your body's way of saying "don't do that shit anymore."
Just get yourself set up to where you can quickly switch between where you're sitting and trimming and you shouldn't have anymore issues.