For your situation and minimal investment I would suggest a tent with a good quality sleeping bag, lantern, cooler, folding camp chairs, air mattress or cot and minimal cooking tools. You may want a propane heater if cool in the evening/am or drying gear, sounds like everything else is already available. The other option would be a small pull behind trailer or truck camper.

The 2 areas I hunt regularily where staying the night is required we have cabins. I still own a tent and wall tent for going to areas that are less than regular. The cabins are nice when it rains or extreme cold but the tents will also work, the only must for me is the ability to dry out clothing & boots for long duration hunts.