Presumption of Guilt In Rape Cases?

Is it possible to reconcile Abyss2hope's suggestion

To use the consent defense, what is needed is not proof of lack of consent (stereotypical resistance) but proof that the alleged victim gave true, legal consent. If the alleged rapist says the alleged victim consented then proving that claim should be the defense team’s burden.

with the presumption of innocence on the part of the accused? It would seem that, in the situation above, the burden of proof is placed on the defendant rather than the plaintiff. Additionally, what kind of proof would satisfactorily demonstrate consent? Absent physical violence a plaintiff can still claim coercion. This is an especially difficult charge to counter given that the reality of the alleged coercion is determined, in large part, by the subjective mental state of the plaintiff at the time of the event i.e. its epistemologically impossible for the defent to prove that the plaintiff didn't feel coerced. I still claim that a better heuristic for assessing whether a particular sex act constitutes rape is whether or not a reasonable alternative to engaging in sex is available.