Could you place the cursor just above the ASCII art and then wrap from there to the top of the document?

For that, you could place the cursor above the ASCII art; press (ma) to set marker 'a'; (gg) to go to the top; (gq`a) to wrap until marker a. ;)

gqG also does violence to some plain-text formatting, such as numbered lists or other short sections in which a specified line length or presentation is preferred.

Long lines and wrapping within the text viewer is probably your best bet.

Ah, I do see your point!