Re: 3 football fields?
Big problem - the Wales is pretty clearly defined in terms of area, subject to minor differences between high and low tide. Although this may change when we ciaim 'Herefordshire' after indy.
But the Rugby Union pitch is a variable unit. In the outmoded non-Reg units used by the real world, the Rugby Union pitch (n.b. not 'field') can be 68-70m wide by 94-100m long, so a 9.5% variation is permissible.
I think stick to the micro-Wales, clearly defined as 20779 sq.m. or about 3 rugby pitches.