It sounds like right now is the time to plant. The first thing you should decide is where to plant [ in the ground or in a raised bed]. I understand that your growing season is short and that you have a continuous sun shining night and day June through August.
You probably can grow most any veggie that you want. Do the cabbages really get up to 80 pounds?
It sounds like you don't really have to worry about the insect pests that we do in the lower 48 so you should have better luck.
I would suggest that you look around at some of the gardens that are being planted now in your area and ask a few questions of those who plant every year.
You need to start ASAP because of the short [105 day] growing season.