Could you post some builds, via Coriolis or similar?
My CMDR's current T-9 setup looks something like this:
A ship builder, outfitting and comparison tool for Elite Dangerous
s.orbis.zone
I usually slap some guns on it so I can kill NPCs, but the loadout depends on what i can spare.
It's a shorthaul trader/mission runner for BGS work, so i don't really care that the jump range is crap...I just want to keep a lucky shot to the FSD from triggering a malfunction right away. The SCO is a new addition to this setup that I use mostly to break out of gravity wells.
In general, if I'm hit with a CMDR tether, I'll make sure I have my escape jump selected (always have a route plotted), then I'll submit and go silent as I boost away from my jump target, flip to face my attacker (so I can more effectively engage any munitions with the PDTs), then try to boost laterally past them while dumping a sink or two (they'll try to target as they get within resolve range, ideally they waste a fraction of a second trageting a sink). By this time the FSD short cooldown should be about up and i'll start charging my FSD the straighten out to jump, popping the ECM if I still see munitions on sensors. Of course, that's just the general idea...I can adapt to an evolving scenario on the fly. Anyway, unless my attackers are
really on the ball, I'm able to jump.
The moment I hit the destination system, I manually kill the thrusters or FSD in the module pane to force a drop from SC to ensure my CMDR cannot be followed. Then I asess the situation. If I still have missions/cargo that I need this ship for, I'll see if I have any allies in the area who can screen my next approach (usually by attacking my attacker just before I renenter the system). Otherwise I weight how much the cargo is worth (in influence) and how likely I am to make it to my destination before either trying again or abandoning the area to run missions at my B-site.
My CMDR's Corvette trader is just his standard combat loadout with all the biggest optionals swapped out for cargo racks. For medium ships I usually use a Krait MkII, which I run shieldless, with relatively skimpy protection, as it's speed is it's main defense.
My cmdr is an open only trader/smuggler and I've always ran shields but maybe I don't need to?
Shield generators are big and ships without a lot of base shielding need a bunch of boosters.
HRPs stop at class 5. The larger ships don't have to sacrifice that much cargo to get quite a large pool of hull integrity. And if you don't have a shield generator, you get to put the more fun countermeasures in all your utility slots.
Of course, you could consider that once you've been interdicted you've already lost - the skill is avoiding being interdicted in the first place.
It takes a string of failures to lose a ship, but only one success in that chain of events to escape. I'm assuming, for this discussion, that one has been hit with that interdiction tether and decided to submit instead of risk that long cooldown on the outcome of the tunnel game (which I am personally no match for an experienced ganker in).
Moving evasively is a bit of a misnomer for the biggest ships.
Even a T-9 that is moving right is much harder to kill than a T-9 that is moving wrong, or not at all.
Anything more nimble than a T-9, evasion really starts to matter.
A couple of examples...
First interdiction in that video had one ship with FSD disruptors, second had two. Clearly the PDT was shooting them down, but a PDT is not a purely passive defense; making sure it's pointed at incoming munitions (and knowing where those munitions are going to be coming from) is critical to it's effectiveness. In this particular scenario, I was aided by the fact that DG had their FSD disruptors distributed suboptimally (the Cutter is a bad platform for dumbfires, unless the target is running away in a straightish line, which I am not going to do in a slower ship), and hindered by my custom galaxy map settings making it impossible for me to load the systems I could jump to faster than the DG wing could (meaning I had to evade them way more than I hoped I would need to...that video is just a segment of this encounter).
That second video isn't a ganker, just a CODE pirate not adverse to a challenge. My CMDR was never at risk, but I still think it's a good example of the benefits of manuver (in this case to protect my cargo), even in a large vessel.
The ship I was using the first video obviously has shields...it was the multi-purpose vessel I used to accompany DW2 before I diverted to Colonia. Same ship is in the second video, but I pulled all the shielding in favor of more cargo and countermeasures as ran missions. That's when I ran into Harry Potter and Deathdingo, who must have decided chasing me around Colonia was more entertaining than taking shots at the increasingly slim explorer pickings.
Why would you not have PDTs? All my trade ships have at least half of their utility slots full of them, sometimes all of them. I also have plenty on my combat ships, since when shields drop, you just know you're going to get targetted with missiles, especially in combat zones, and they can ruin your day.
If we're talking about ships with relatively weak base shielding and relatively few utility slots (which includes most of the Lakon ships), the PDT is much more of a trade-off. Shields are a much less situational defense, so if one is going to use them on these ships, going all in on them may be the best bet.