Woolworths department manager pay negotiation

I'm about to move up to nightfill manager at my woolworths and I'm looking for some advice on my contract. The shop is pretty remote and I hold abit of an advantage as they would have to pay massive overs to bring someone else in from another store as they are hours away. Currently take home 1200 a week as an assistant working 38 hours but workload will increase to around 50 hours any advice is welcome