What were the early indications? It was never possible to scale up the project, so what kind of a deterrent would it be, when it was full after a month or two? I believe Israel tried and abandoned a scheme to send people to Rwanda, and that almost nobody who was sent were still in Rwanda - the majority having headed towards Europe.
Also, if it's so easy to simply abscond, then why not just do that in the first place? And why would Rwanda deter anyone if they could just abscond. If you're going to disappear, it really doesthn't matter where you're not being sent.
As for the lorries- isn't the main reason people are risking their lives in boats, because it's much, much harder to cross via a lorry? There was a French right wing politician complaining recently about all the security around Calais, which meant that migrants had to find other routes, or even stay in France.