In the NHK historical drama Tenchijin, Akechi Mitsuhide (left) is making tea for Toyotomi Hideyoshi (right), at this time still a retainer of Oda Nobunaga. Mitsuhide uses a furo upon a hard wood floor and a tsurube (釣瓶) mizusashi, but what I find most interesting is how he is sitting. This photo captures him turning from shomen to face Hideyoshi, but he sits cross legged throughout making tea. Seiza was not the only correct way.
Nota bene, Akechi Mitsuhide was the father-in-law to Hosokawa Sansai, one of the seven disciples of Rikyu, through the marriage of his daughter, Gracia.