You are creating a Diorama and as Jim observed, the lack of figures will make for more consideration of layout and 'story telling'. The Tompion would be best put somewhere where a crewman or worse an officer
would not trip over it, but will also be in the diorama. What scale is the model? There may be suitable figures if the model is in a standard scale (1:32nd, 1:48th etc).
All in all a lovely piece and one that will have so much detail for your friend to find. I hope he is pleased with it as you put a lot of effort in your work, and to hear that someone would query that becuase it isn't a full ship model would be sad.
As regards the crew's life aboard, it was hard and in action could be dangerous, but the Navy fed their men well if monotonously, and as Nelson is supposed to have said regarding food: 'What the eyes cannot see-the heart shan't grieve over'. Meat and fish was often salted and dried for the winter months when times were less plentiful, and I doubt that the sailor's families at home would have had half what they got as a daily ration, certainly not as much meat!