Custom branding options via API

We've done our initial production rollout of our new feature that includes eSignLive integration - everything is working great, but one of the early feedback items that has come back our way is the desire to do a bit of custom branding around the signing session. One of the items requested was to place our custom logo on the top left of the signing session - this was very easy to accomplish via the API (settings -> ceremony -> layout -> brandingBar -> logo), but I believe there is also a way to customize the look and feel of the "Thank You" dialog, correct? There is documentation here - http://docs.esignlive.com/content/c_integrator_s_guide/sdk/k_customization/customizing_the_signing_cermony.htm#Customiz2 - which even shows some JSON that seems to indicate how one might go about customizing the "Thank You" dialog box, but it's provided in the context of the SDKs, it seems. I haven't been able to track down the equivalent feature on the API side (this is the closest I came, but I can't seem to find any references to the "Thank You" dialog here - https://developer.esignlive.com/guides/feature-guides/signing-ceremony-customization/#rest-api) The question has also been raised as far as what our options are for custom styling the various emails. It is my understanding that eSignLive has 2 high level options available - we can either let eSignLive handle the sending of emails OR we can work with you guys to send emails from our own internal SMTP server. Seeing that we're doing the former, my understanding is that we don't have control over any styling beyond what is exposed in the API here: roles -> emailMessage -> content. Is that assessment accurate, or are there other options available? Would we have a wider array of options if we brought our own SMTP into the fold? Thank you! Nick