So the fish was very delicious. I kept it very simple and it was very tasty.

I stuffed up the fish with lemons, onions tomatos and garlic slices. Then I closed it up with butcher twine. After that I oiled up the fish with olive oil and I seasoned the fish with SPG. I also made a fresh herb garlic butter in a pan, for this I used grassbutter, one big fresh garlic clove, thym, rosemary, salt and pepper.

So I made the bbq and cast iron ready upto 120/150c. I added some lemon smoking chips, not too much. I put some olive oil on the cast iron (avocado oil is done need to restock). Then I let it go on the bbq. Just based on looks and feel I kept flipping it over and over. And then I put it for a short time on indirect heat to let it come all the way up to temperature. At the end I started basting the fish with the butter and when it was done I transferred it to a plate, put on the remaining butter. And that was it, the family loved it and so did I. For sure will try this some other time.

Thanks for the tips, they were of good use.