In reply to:
A. lots of guys like big boobs, but
B. most guys are also extremely cheap, meaning that
C. very few guys are willing to spend serious money for the pleasure of seeing huge boobs, but
D. if those boobs are bouncing by and can be seen for free ...
This would seem to suggest that the appropriated business model for huge boob entertainers would be one in which she collects eyeballs for advertisers. That is say, one in which revenue flows exclusively from sponsors.
It's unlikely, however, that most advertisers will care to support explicit porn. A profitable approach, then, it seems to me, would involve the huge boobed entertainer on display in an asexual context. A sufficiently articulate entertainer could, for example, host a talkumentary show produced for a niche cable channel or a local TV station desperate for original programming --
Your Pet's Health,
New England Gardens,
Native American Cuisine,
American Bed and Breakfast, etc. The hostess would dress just modestly enough to eliminate the appearance of blatant sexuality.
I am absolutely certain that the ratings for such shows (e.g.
Skeet Shooting with Melanie or
Melanie's Kitchen) would be consistently high.
There must be something wrong with my thinking, however. Otherwise this would have been tried successfully years ago.