Let's fix TW Sandbagging....

I see most of the top guilds complaining about the TW system as well, so it's not just complaints from smaller guilds facing high end guilds with less than 50/50 signed up.
My old guild used to have a real issue that lots of people signed up, set (maybe) their defense, sometimes just a few squads and then screwed over the rest of the guild by not showing up for offense.
My current guild have a pretty well enforced "show up if you sign up" rule which do mean we rarely see 50/50 wars, however we do see that everyone who signs up sets their defense and engage in attacks. It also means that we see wars where our opponent are pretty outmatched, particularly if they signed up 50/50 and have 10 members not putting in any effort.

My advice, if you are the guild with more signed up, is to adapt your defense. E.g. if you would usually set a zone of JMK another zone of Leia, one with Jabba etc. but have 5 more members than you need squads, then take all the strong squads left over and stick them in a spillover zone.
This will in effect be pretty similar to forcing the "sandbagging" guild to set more teams, as you can set all your meta squads down, and force the other guild to use secondary counters for those squads set by your "extra" teammates.
I do get that if the match is very lopsided this might not help you win, e.g. if opponent have many more Ahsokas or similar than you do, however it is something that should be able to at least balance the scales somewhat. And something I only see a few guilds do.