Plans say assemble on the floor, but trialled doing it on the table and it seems entirely workable. Me being 6' 3", and Nat being about 5' may explain this. Took two goes to get it all the right height.
Checks reveal the sides are a smidgen overlength. Strangely, the sides measure the right length, but when mounted the distance between the temporary firewall and F22 is too long. Fixed.