Huo Ling, having raised well in the palace, is only a little shorter than Yi Bing. Yi Bing, although has some muscles, but not to the point they are exaggerated. Also, since no one has since Huo Ling for a long time, except to the people he interacted with the past years, they won't notice 'Huo Ling's change tonight, unless they are someone close to Huo Ling, or one with discerning eyes and knows Huo Ling.
The former's example is the royal family, and Hao Baiyun. Meanwhile, the latter's example is Gu Xingfeng. Unless any of them would expose 'Huo Ling's identity, which definitely they won't do, then 'Huo Ling' can do his task peacefully tonight and act like the original one, while having the original one in his arms act as his female companion.
