Ok so we have 80 acres all told with 28 BoH, that leaves 132 acres for Citywalk, the road connecting to Manor Road, the Transport Hub and car parks. I really think they can accomodate more Park 'space' without being overly constrained. The main car park will be at worst 70 acres, leaving 60 acres for everything else.
Honestly I think we should wait until they drop new concept art before denigrating the Park as too small or not enough for the crowds expected. The current art we got is oriented the wrong way, vague in multiple places and the 'expansion pads' are far more than 17 acres. I'm also not entirely certain that the planning docs Core Zone layout is set in stone - there's no actual concrete figure on the maximum size of the Park in the Core Zone, only a hard minimum.