I totally agree with starting with what you have. It won't be everything, but you don't know what matters yet. Set it up with enough racking for your nights out and see what you think. Or go the bikepacking route with rack-less luggage.
If you're getting off the pavement, you'll want to think about gearing and tire adjustments to the current bike. Gearing for loaded off-road will have to be lower and you'll figure that out. I am very particular about tires and ride the widest lightweight tires that fit in my bike.