With the realization that this might be quite the obscure question...
I have read more than once that a cause of this musician's death was a drinking spree brought on by receipt of a letter from a film studio late winter/early spring 1931 that he (or he and what presumably was his working band) was invited to Hollywood to provide music for a western. This was apparently quite welcome as Poole hadn't recorded since the preceding September.
I have watched a fair number of westerns from 1931, and, assuming that his death in May caused another group to be substituted for Poole's Ramblers, I really have no idea what studio could have contacted him. There is singing in Maynard's 1929-30 Universal westerns, and in several of Bob Steele's 1930 Tiffany efforts, but by 1931, there was less instrumental music in B-westerns, aside from Tom Tyler's West of Cheyenne, but that was released in March 1931, and thus pre-dates the letter.
I did recently watch two Bob Custer films, Headin' For Trouble and Quick Trigger Lee, which were released in the late summer/early fall of 1931, and are possibilities, as there are musical numbers in each by a group (including someone playing a cello in the latter film!) but would rinky-dink Big 4 have made an offer to a known recording artist such as Charlie Poole to provide a few musical numbers for Bob Custer westerns? That doesn't quite sound right.
In any case, if anyone has an interest in/knowledge of Charlie Poole, I thought I'd ask. Supposedly, his spree lasted ten weeks(!), so that means receipt of the letter in late winter. I guess the studio wasn't in any rush for him to show up if he had that much time to drink so much and so often.
Open, general discussion of music during the era of classic/nitrate movies