You are talking about raiding scions.

There is a very simple solution to not having your gear stolen whilst you raid scion.

If you miss it, that's your fault, because it is something 100% under your control. Much moreso than running out of preps whilst defending against sustained attacks, which is often something under the control of the attackers.

There are other situations where you might not have control over whether you get robbed blind by nightwalkers, but when you raid scion, that's not one of them.