Hiya! I'm a newb too, so don't take my input too seriously. I'm also wanting to do a paludarium of sorts, but I won't be using a divider.
From what I've seen, this seems to depend on a lot of factors. Such as; is the divider through the narrow point or the wide point? Will the pressure from both sides be roughly equal, or are you using a false bottom for the terrestrial side? Or heavier substrate?
Most people, from what I've seen, simply use silicon and don't have problems with reinforcement. I'd, personally, fill the water side completely and let it sit for a while, see if you spring any leaks or if it pops out of place.
For creative solutions; I saw one guy slant the divider toward the land portion. He did this because the pressure from his water was much lower than the force of the thick and heavy substrate for the land. He just made the divider itself into a steep beach of sorts.