Nothing makes me ravenous like cardio. I'd do some LISS 20 mins in the AM and again in the mid day / evening if you can (the second session always makes me hungry AF). As others have said, you can't get 5000 calories in 3 meals. 6 meals per day, at least.
Other tips for appetite - eat HIGH CARBS. There's a reason the big boys love eating Cream of Rice. Lots of carbs with minimal food volume. Regular rice is great too. Rice cakes with some honey on them. Dried fruits are also very dense sources of carbs, though they are simple (sugars), so not great to rely on them other than for around workouts.
You don't need as much protein as you think you do to gain mass. 200 g daily would be fine. be careful with the fats. They can provide extra calories but also slow digestion and make you feel more satiated, which isn't great for the next meal and the meal after that.
So instead of just plain chicken and rice, you can add 2 tbsp EVOO and a few eggs, make it a chicken fried rice. That will give you another 300 calories of good fats. And something like 200 - 300 g cooked rice with 5-6 oz chicken. Steak is great too, but harder to digest. Fish is easiest to digest, but just tastes like shit really (whitefish I mean). Salmon is good, but the fat can fill you up.
Also, protein shakes. Portable, easy, you can add in all kinds of shit for extra calories. Nut butters, banana, drink it down with 70 g of dried mangoes and that's another 550 calories on top of the protein and liquid.
You need to experiment with what foods agree with you and what you can digest. Cream of rice is always a winner, but I would add some fat to it with nut butter or something. It can really spike your insulin and leave you feeling lethargic especially if you only have it with whey. Adding some almond butter to mine totally fixed that.
Gear-wise, boldenone tends to bump appetite for most users.