I am playing in a Spycraft 2.0 campaign. The bulk of my party is not very tough or even combat oriented so it is up to my soldier to draw fire and to steal a term from another game "tank" in many of the combats. I've gotten my DR very high, but per the rules, every hit that completely fails to penetrate will cause 1 non-lethal, which accumulates pretty fast if I'm getting shot at repeatedly and as soon as it hits my Con I'm running the risk of getting knocked out. Beyond the obvious like taking cover, are there any ways I can mitigate or slow down that non-lethal damage so I can stay in the fight even longer?
If you haven't already, take the Iron Will feat...it increases your thresholds for both subdual damage and stress damage. A longer-term solution is to get 4+ levels in the Brawler expert class to also add to those thresholds. The Explorer class and some unarmed feats also provide some ways to up your CON score or increase your threshold.
I'd still look at what you can do to increase your Defense. Sounds like you already take cover, but maybe there's another feat or class ability that could help you out.
Damage resistance is potentially an option, though the rules get a bit fuzzy since DR is applied before resistance. This might give the illogical case where a small hit that is totally absorbed by DR means you take the subdual damage, but a bigger hit that gets through the DR and is absorbed the resistance means you take no subdual damage.
And, borrowing some more MMO speak, maybe you need to spread the aggro around more. Sure your party is not very tough, but maybe they can soak a hit for you to keep you from going over a threshold.
Frankly though that rule is in place to keep some danger in place for DR gods like yourself. You can mitigate it somewhat, but the GC in me hopes that danger never totally goes away. :)