Is it possible to run a noise simulation and an AC simulation independently from one another and display the results in the same plot?
Or better, is there a way to determine the SNR in one single plot?
To the best of my knowledge, you cannot display the results of different simulation types in the same graph.
However, you can export the numerical results of each of these individual plots to a .txt file and then graph them in another program. The link below shows how to export waveform data.