You dont say what kind of boat you have, it could be helpful.
The backstay is used to controll the bend in the mast and to a degree the forestay tension.
But to make this possible you will need a masthead fitting on the mast where the attachement of the backstay are placed some inches (6?) further aft than the aft wall of the mast section. These masthead fittings are also angled so the aft part sits higher than the forward part.
With a setup like this the mast should be adjusted with a little bit of prebend in the mast.
I would gess that since you have the setup you described your mast is of this construction.
I would not remove the hydraulic backstay adjuster on my boat. If necessary it should not cost so much to service the adjuster.
You can replace the rod with wire (I have a wire backstay with hydraulic tensioner).
On my boat adjustable length on the backstay tensioner is so short that I have to put in some bend in the mast before I can connect the backstay to the backstay tensioner (the base prebend)