Well, not really – the January 1975 second draft established the basic plot structure, and the August 1975 third draft set up the character dynamics we know (save for Governor Tarkin, who was added as an additional villain in the fourth draft Jan 1976 script).

But I do think it may have been something Lucas talked about with someone at one point, hence the model being created.
Similar to how Luke told Ralph McQuarrie in April 1975 that he was considering having a female protagonist, and McQuarrie drew concept art accordingly for a month until Lucas changed his mind and started thinking about the third draft.

Lucas was extraordinarily good at throwing out interesting ideas in casual conversation – the Holiday Special premise began as an “alien fairy tale” bookend idea he suggested offhand for the first film, and he also considered a scenario where Luke, Han, and Chewie all get captured on the Death Star and rescued by Ben. However, Lucas’ slow methodical style of writing (and his tendency to preserve language from previous drafts whenever possible) meant these never reached a script page. The Skyhopper idea may have been a similar case.