O Lótus da Neve (2015)

Both main female characters end up being "forced" to dress as males by their families. Guy falls for her thinking he is gay and girl falls for her thinking she is a he.

Both have a girl dressing up as a guy to go school in around the Joeson period. Both contain two people falling in love blah blah.
Snow Lotus is a lot shorter and contains past as well as present, all about reincarnation and loving people and dreams.
Whereas Sungkyunkwan Scandal is more focused on the girl dressing up as a guy and going to school, entirely in the past.

Same reincarnation of main leads with more twist and turns as you will get to see double role of the female lead as twin sisters.

Again, similar theme. Love from the past reincarnated in the future, both dream same dreams and are searching for clues to who that person in the dream is. and again, I thought 'Snow Lotus' was the better of the two. But if you enjoyed one - you might enjoy the other. Snow lotus has a better ending.

Though not as a much of a gem as Splash Splash Love - in my personal opinion - Snow Lotus still managed to touch my heart in a similar way by covering two of the same themes: love, and the blending of the Joseon era with modern day. It's also only two episodes long.

Both are short and sweet drama specials dealing with past lives and immortal love

Both dramas are gender-bender set into the past. Well... Snow Lotus isn't just in the past since it's about reincarnation. But there is gender-bender in present too.