I would take everything I would normally take with me, but maybe a few extra things like more spare batteries, extra coils, an extra detector (if you have one) and a spare shovel.
If you're going overnight or for a few days, bring a tent/swag, sleeping bag, blankets, air mattress etc. Anything you would take camping. There are heaps of camping checklists to be found online. Also bring enough food, water, cooking equipment, clothing, toiletries etc.
Especially if you're going to remote places, bring spare car parts, repair equipment, spare petrol and emergency signalling equipment such as an EPIRP or a PLB.
If you're going off-road, maybe bring 4WD recovery tracks, just in case you get stuck.
A good idea before any extended trip, make sure your car is working fine, so you don't have to spend time with car issues.
Before you head off, spend a lot of time planning your trip (where you're going to be detecting) and also your route and camping site/s.
Hope this helps
