Your 26th march sketch constitutes a good attempt.
The equatorial area strek (almost parallel to the Terminator) is highly probably illusory (see the website http://alpo-j.sakura.ne.jp/indexE.htm for comparison on the dates).
There is no streak refererence showing yours for the 26th date.
However, when looking at the working conditions, you are using a 102-714 refractor, probably semi-apo kind,
we may have comments about.
142x magnification is not too big, but may be too strong with regards the seeing level. Personally on my 102mm I am using 95 to 112x for the best possible Under seeing 5/10, during day. With 150x this is washed images too strongly.
The 102-714 may be also not good enough, I used in past a 110mm F7 of same design, working well on the moon but failing on planets as the venus and mars, and wonderful saturn images. On small features low contrasted, this was a strong fight for collecting few things.
Its "strehl" ratio, good on contrasted features, more than average on the lower.
For a stunning status that: the 102 F10 ACR worked strongly better than the 102 semi-apo, even the 102 F6.6 ACR by vixen.
So here the OTA status may be the limiting factor.
As you reported delicate features anyway and subtil light variations on the disk, an higher OTA with an higher stehl ratio will boost your data, surely.
This is my feeling globally.
After, the filter serie to be used will not be for purpose of enhancing only the contrast image but to see what happens into color segments.
My opinion about.
Don't hesitate to reply, this is for exchanging on the topic.
Good skies, keep healthy.