By 1945, what is needed is a benevolent dictator that does the right things. Of course, aspiring dictators aren't benevolent. It is extremely rare to find one truly committed to modernizing the country and improving the condition of the masses. Even those whose instincts are benevolently paternal, are still so paranoid of losing power that they'll engage in repression. There is always the point where things have gotten good enough, that the educated and middle classes created by the dictator seek to share some of the power (or push him out entirely), and dictators are rarely willing to retire.
Regardless of who is in charge, these are the things they would need to do (and which for the most part is opposed by almost the entirety of the Haitian elite who benefit from the current system).
1) Implement educational reform base on use of Creole, not French, in the classroom. You will never have literary if you aren't teaching the vernacular language. You can't have upward mobility if fluency in French is the pre-requisite for any kind of higher education or professional certification.
2) Reform land tenure in order to encourage the creation of independent farmers who can be economically successful and take care of their own land to prevent soil erosion.
3) Invest in local infrastructure to provide basic services to the people - roads, sewers, health care, electricity, and telecommunication lines. Infrastructure in Haiti instead is mostly limited to allow export of agricultural commodities that enrich the elite.
4) Program of mass employment to provide hope to ordinary Haitians, give them job experience, and give them money to fill their pockets. Although many Haitians do not have many job skills, the extent of Haiti's poverty is so much that even unskilled labor can provide a lot of useful work.
5) Crack down on the massive corruption of the Haitian elite which consumes not only most of the country's wealth, but the efforts of international charities which attempt to alleviate some of causes of poverty.
6) Control the rivalries of the Haitian elite - often between the families that are mostly mulatto versus darker skinned. This is the cause of much of the instability of Haiti.
7) Implement population control policies. Haiti is just too populated for its size and level of development. Family planning and birth control are essential.
There are serious social problems caused by the more superstitious elements of voodoo. Fatalism, superstition, and a belief that human effort won't change things do impede progress. However, the social, political, and economic superstructure of Haiti is sufficient to do that on their own. Poor people in Haiti don't believe it's possible to move up socially or improve their economic conditions because there are real obstacles impeding them. If they are removed, voodoo will slowly be reformed as the worst superstitious elements are ignored by a population that sees they can improve their condition.
The problem is that this program of reform will be opposed by 90% of the Haitian elites. The masses aren't powerful enough to allow for someone to base their rule on them. Foreign support (and for Haiti, this must inevitably mean the US) is crucial. So ultimately this means some form of US supported dictatorship. However, we've seen this IOTL and know that while this may be a necessary condition, it is not sufficient. US supported Haitian dictatorships did not embark on these reforms, and Haiti did not improve.
Ultimately, this is a search for a fantasy figure - a benevolent reformer who nonetheless is willing to brutalize the Haitian elite to break them so he can implement these reforms, yet can retain the support of the US government during the Cold War, and somehow get the necessary funds to make the massive investments he needs (perhaps a combination of residual export commodities, foreign aid to the government, and NGOs performing charities).
If there is any real Haitian figure who comes close, I'd be interested in learning his name.