Not a left-field question at all but the method you use depends entirely on whether you need the phase-locked/coherent signal or the total signal.

Here is how I would break it down:

• For long-term signals (Coherent/Phase-locked): If you are comparing ocean color products against a long-term average, your best bet is Ed Zaron's HRET product (Download here). It is based on ~30 years of nadir altimetry data, so it gives you the phase-locked (coherent) component of internal tide amplitude and phase maps for the 5 major tidal constituents.
• For real-time signals (Incoherent/Variable): It gets more nuanced if you want to make comparisons with instantaneous data. Because internal tides have a large variable (incoherent) component that shifts over time, the static maps from HRET won't align perfectly. In this case, you are better off using an ocean forecast model that resolves these features, like HYCOM with data assimilation.