Can't tell you just how much I hate that setup on the 200Tdi. Has to be the one thing that whoever that was in charge of designing this excellent engine had a brain fart on.
Attempt to power anything that draws anything above average amps and the alternators start eating those small belts for breakfast.
Don't know if its something you would want to consider, but electric power steering pumps from say an old saxo work a treat....they only work when required and don't really require any special modifications aside probably having your hoses extended.
And should they fail, doesn't take out your water pump drive.
Next course of action then would be to machine a hub with the stock PAS drive pulley to bolt to the back plate that held the pump, retaining your existing belt and tensioning setup.
Too much?
I have a workshop with all the toys and weekends can get boring sometimes.