You could combine the two, but I see Muay Thai as a complete striking art in an of itself. The litmus test for me is to watch fights between karate practitioners and Thai boxers. In most fights, the karateka gets completely "owned" by an experienced Thai boxer. This is because Muay Thai is the "Art of 8 Limbs." Thai boxers throw some devastating elbows, shins, and knees in addition to the punches and kicks that most karateka are used to defending against. It's not that there are no karateka who can beat Thai boxers it's that collectively Thai boxers "appear" to be better strikers than "most karateka." Karate does produce some tough fighters who can beat Thai boxers, but they tend to be the exception, not the rule.

If you can actually throw Shito Ryu strikes at a Thai boxer that he doesn't see coming a mile away, then go for it, but I think it would be better for you to transition from Shito Ryu into Thai boxing if you truly want to be able to hold your own against Thai boxers. Like all of the great fighters of the past, you should use what works, and abandon the rest.

Personally I would not combine it. I would go with something completely different, like joint locks, throws, etc. I think you will probably struggle with learning two arts whose main focus is on striking.

When you decide to cross train look at techniques that might compliment what you already have and then pick a teacher who teaches those techniques rather than picking styles. All styles can be taught many different ways and for many different reasons and by just picking a random style you may not be getting what compliments what you already have.

You can not combine these besides you obviously don't have a clue or you wouldn't be asking. Stick to video games.

i know you can cause it is a striking art and shito ryu and muay thai is like the same. they are have the same techniques and they both can be use for self defense and i want self defense