I'd do it like SYDERLK - sort of - except maybe NOT on the steepest part first. I'd start near the top, going across, and keep moving farther down the hill. Stop on each pass as it gets successively steeper, and check it by getting off the tractor on the uphill side and try to tip it over by lifting on the uphill wheel, you will get a good idea how far you can go.
Don't worry about it actually tipping over (in this careful, methodical) test. When you get even close to the limit, it will tip up against the front axle stops, lifting one wheel, and will stop tipping. You kinda don't want to get that far because then you have to wait 'til your wife gets home so she can hang off the uphill side while you back off the hill.
My tractor (
B2710) I think is very similar to your 2620 in size/weigh/tipping. I have a vey hilly property, have a constant battle with lifting a rear wheel, it happens all day long sometimes. For a consistent slope you could rig up some (secure!!) counterweights that you put on the topside for that hillside cut. To add a safety factor.
Maybe sandbags in the FEL topside but make ---certain<--- they can't ever slide down to the lowside. And this would be with loader just skimming the grass.