EDIT: Turns out, CivisRomanus has made the "fix" to Bethesda great idea of the ignore-dr added damage mechanic
You should go to his mod page in order to see many improvements to the game.
Edit2: I'll make the standalone edit to swampfolk soon.
Edit3: the mod is made by editing the stats in GECK. Mod has been cleaned using FO3edit quick auto clean.

Swampfolk condition is said to happen because of inbreeding and the radiation from point lookout area pollution.
Even so, TvTrope list them as demonic spiders (annoying enemies that is hard to kill and deadly).
Bullet sponge and having added damage to their weapon (including the tribals), these area specific super mutants (no, seriously. GECK classify them under super mutant) are much more deadly than enemies on capital wasteland.
the strongest even have deathclaw stats AND reach. Ya know... inbred? as strong as deathclaw? that's no more "It just works" level.

I've change their attack to 5 (-1 damage from super mutants, but they have high crit stats that cannot be edited.), agressive radius from 3000 to 1000 and lower the HP and the attack of the strongest type.
Hopefully this make the DLC still fun as many user has reported but doesn't change it into a nightmare where these swampfolk is as strong as a freaking deathclaw.

I also edited the added effect damage which hopefully cover all Point Lookout DLC weapon.
real funny bethesda. adding an unresistible damage to tribals. real funny.

Hopefully this mod can help you and me, who finally will try all the DLC that is needed for the unofficial patch.