The ideal off season is going to be based around diet, pushing the right amount of foods. Just like your contest prep, pay attention to your diet and systematically building the carbs and fats, while maintaining enough protein to keep adding muscle. As for gear, it doesn't need to be complex. Test and an anabolic like Deca or EQ. I would not use Trest aka MENT in place of test. If you are looking to take it to the next level, consider using insulin.
After your prep, I would suggest dialing back the gear and staying on test for a few wks. Then if you plan to recover your natural production, begin working on that. Otherwise, back down to an HRT dose and focus on getting the diet right for muscle gains. Then it wouldn't be a bad time to get some lab work done to see where you're at, check your organ function and cholesterol before stepping on the gas again