@1ORIN
there are a lot of sugarcane uses beside sugar, the by product of sugar are molasses.
molasses can be fermented into rum, which was the fuel of sea trading. it also can be given to cattles, to fatten them faster.
the other is bagass/cane pulp, can be used as fuel. but thats not a problem.
by using Co-op or guilds in some case. the guild/co-op can negotiate a fairer price for the farmers instead. and they usually can give "loan" to farmers. such as seed, fertilizer, food, etc..
another solution is to not trade all the sugar, but educate on how to process the sugar to another "refined" product and make it the speciality of the area. candy making probably, or liquor products?
if, a big if, they succeed, it will probably attract a lot of other business/trade. since more money means more spending. which in all can be taxed by the kingdom?
so even if they can't taste the sugar now, they probably can in the future.