What evidence do we have that Blind Bartimaeus approached Jesus naked? In Mark 10:46-52, we have the story of Blind Bartimaeus Receives His Sight


  So they called to the blind man, “Cheer up! On your feet! He’s calling you.” 50 Throwing his cloak aside, he jumped to his feet and came to Jesus.


I've seen some treatments of the story that claim Bartimaeus would have been so poor as to possess nothing but a mat and a cloak, so would have come to Jesus naked. Thus, extra theological meanings are drawn about coming without any works or individual merits, the scandal of free grace etc.

A google image search turns up many inspiring depictions of the event from historical paintings or woodcuts, but none hint at nakedness. But many hardly depict a desperately poor person who's thrown off anything.

What evidence do we have for this? What prominent theologians have made this claim?
I do not know who else has said this, but one prominent commentator who is of this opinion is the
Venerable Bede (672-735), in his commentary on Mark.1
He does not offer historical reasons for why the blind man might have been naked, but presents
his nudity in the context of the doctrine of being "born again" in Christ. As you say, this
involves casting off the old ways, like taking off ones old clothes (compare Mark 2:21).
In imitation of Christ, for which Bede cites John 12:26, we must re-enter the world (metaphorically)
naked and vulnerable, knowing that we may face terrible hardships; and we choose to humble ourselves
rather than submit to false worldly comforts. 

My fairly free translation of the key passage:


  Since there are many, who so they may merit the treasure of eternity in heaven, cast off worldly ways 
  and follow naked the gospel of life, it is rightly said of the illumination of the blind man:
  Who throwing his garment aside, leaped up and came to him.
  He indeed throws aside his garment and leaps, coming to be illuminated by Christ, who,
  with the snares of the world discarded, hurries with bold and eager steps to the granter of eternal 
  light. [...] See, how the Lord and creator of the angels, in his taking up and joining with our
  nature, came in the womb of a virgin. But he did not wish to be born in this world from the wealthy,
  but chose poor parents.2


Latin nudus may not mean precisely "naked", but at least refers to a condition of vulnerability or destitution. Even if Bartimaeus was not strictly naked, he was at least making a "leap of faith" in throwing his cloak aside: discarding what little comfort he had in order to follow Jesus.

1. In Marci Evangelium Expositio, book 3, chapter 10. In Migne's Patrologia Latina,
vol. 92, p238-239.
2. Quia [...] ut plurimi, relictis mundi facultatibus, nudi evangelicam vitam sequerentur,
quo aeternum in coelis mererentur habere thesaurum, recte de illuminando caeco subditur:
Qui projecto vestimento suo exsiliens venit ad eum. Projecto quippe vestimento exsilit,
ut adveniens illuminetur a Christo, qui abiectis mundi retinaculis, expedito mentis
gressu ad largitorem aeternae lucis properat. [...] 
Ecce cum sit Dominus et creator angelorum, suscepturus naturam nostram quam condidit,
in uterum virginis venit. Nasci tamen in hoc mundo per divites noluit, parentes pauperes
elegit.