Is there any evidence that Martin Luther considered any of the Roman Catholic clergymen who lived in the centuries preceding his own lifetime (evidence related to those living in the centuries immediately preceding his own lifetime is preferred) a part of the Universal Church?
Luther viewed Thomas Aquinas as one of his adversaries. He saw him as someone who interpreted the Bible according to Aristotle. There are many references against Thomas in Luther's writings. Here is an example when speaking against indulgences:
They are far more foolish than the Pythagoreans who assert only those things which Pythagoras has said. These, on the other hand, assert those things which the Pythagoreans doubted. But let us come to the source and fountains of these rivulets, that is SS. Thomas and Bonaventura. (Luther's Works Volume 31, P146)
Catholic Saints, Monks and Nuns are generally viewed by Luther as totally lost as they relied on their own works for salvation. However, Luther had his own secret hopes that many of them still found faith on their deathbeds. After referring to St.'Francis, Dominic, and others', Luther says:
I do believe, however, that the aforementioned monks recognized and acknowledged their error before they died and finally rested all their hopes on Christ, the true and only Light, through whom alone man is illumined, and not through any other. ...Had St. Bernard not died in this faith, he would have gone to the devil and into the abyss of hell with his monkery and monastic life. It is the same with all the monks in the papacy. No matter how holy and ascetic their life may have been, if they were saved, they must have come to this same realization. (Luther's Works Volume 22, P52-53)
On the salvation of non-famous monks, etc. Luther said:
I once saw a monk who took a cross into his hands and remarked while the other monks were boasting of their good works: “I know of no merit of my own but only of the merit of Him who died for me on the cross.” And in reliance on that merit he also died73 In the papacy it was customary to admonish a dying monk to be mindful of his own merits and works and of those of others. And in that faith they died. But just as the pious monk died a blessed death, relying solely on the merit of Jesus Christ, so many a wretched criminal on the gallows has been delivered from sin and saved through faith. That is how St. Bernard was saved. He was an exemplary monk. (Luther's Works Volume 22, P359)