The feather action on your hyd valve should let you work as slow as you want. After the stump is pulled, the pressure will go down according to the weight of the stump. If you install the gage, you will see the working pressure at all times.
The thing about the pressure, is that you may need all of the pressure the pump can provide, and after you break the stump out of the ground, the pressure will fall quite a bit.
With nothing attached to the cyl, very little pressure will extend the ram, or pull it in.
After the stump is pulled, you can switch to single chain and do whatever.