I’ve done a lot of ganking, and also frequently move compact high value items like blueprints.
I strongly disagree with your advice here. Combat ships are far superior for hauling blueprints - and interceptors are better still. Brick tanked T3 cruisers can be hard to crack - Marauders are harder still. (I FCed a gank attempt on a Marauder in highsec a while back, we had 28 people, and we failed - they tanked the damage as well as the mission rat damage they were also taking).
My default approach is as follows:
<2b (e.g. unresearched Dreadnought BPO): Carry it in an interceptor. If going through low or null, refer to the starmap for ‘Podkills within last hour’ and avoid all systems where that number is >3. (4+ podkills in the hour is a fairly reliable indicator of a smartbomb trap, the only thing that can kill an insta-warp interceptor). Always avoid Tama and Rancer.
If the goods are not compact, an Occator (or other deep-space transport) with X-type hardeners, a cloak and a MWD is one alternate option. The other option is a freighter with an escort (see 5b+ for escorts)
2b-5b (e.g. highly researched carrier BPO): Carry it in an interceptor. Avoid all lowsec systems, except the lowsec alternate route to avoid Uedama.
5b+: Scout ahead in an interceptor on an alt, alt stays one jump ahead and carries bait that is of obvious value and renders them ‘worth’ ganking (e.g. 250 PLEX). The valuable blueprint also goes into an interceptor.
I make damn certain that I do not tell anyone about these moves.
If anything sets off my danger sense, I dock up and log off for at least 2 hours.
Lowsec is fine for these moves - it’s often better than highsec because lowsec is so empty and you have a scout.
The other top defense against ganking is to conduct ganks yourself. You will learn a lot from doing so - learn how we operate, how we select targets, and what strategies frustrate us.