Take the opportunity to build something mental.
4 distinct two-tier stands, bottom tier bigger than top tier, each with a roof that jacks up and down to hide the top tier if not in use.
Standard configuration (14,000 seats - 4.5k along the pitch, 2.5k at each end), single tier all the way round, then can lift the roof on each individual stand as required. Maximum capacity 22,000 (top tier along the pitch 2.5k, at each end 1.5k).
Recycle the parts off old decommissioned jack-up rigs, have ourselves a sustainable, dynamic stadium with a bit of character.