What do you mean only two XXL Units? you can take up to six XXL Units (an XXL unit takes up four hanger slots and can only be placed as the first unit on the team, of course), with one on each team, and one for each master. I don't know why you would, but you can.
btw i feel this a good time to remind you guys that sea of thieves was made by rare, who also made DKC1-3 and DK64, alongside banjo kazooie and conker's bad fur day