Yeah, looking at it there probably is enough space. And do you mean a ground plane on the top layer as oppsoed to or as well as the bottom layer? I’m not familiar with the so-called flooding.
For a 2 layer board like this I normally put ground on both and join them together with vias as needed. With only one layer of ground which is also used for tracking or parts you end up with some big slots and cuts in the ground. By filling both with ground and joining them together either side of any larger cuts (where practical) you get a nice solid ground everywhere.