Spell Damage doesn't even matter for SK/RNG synergy, really. It's all about Touch of the Cursed being so nutty with bows and the fact that Theft of Life makes your crit heals from it 5k+. And we're just now entering the era of insane itemization in EQ, where they started slapping ALL STATS/ALL RESISTS on almost every piece of gear. I'm at 125HDex(need to get that 150 breakpoint but I've been lazy in Luclin because I hate it)2300atk, and still have like 250 SD. It's plenty. You will get a lot of it "passively", as the eras go on. And you have leech touch, leechcurse, weapon dance, shield of songs, etc. for emergencies where your TotC isn't proccing. I can practically AFK on almost every boss, even Kera. The only part that matters for Kera is popping all your burn when he hits the 25% so you don't get adds. But I afk every boss in VT no problem and it'll be even easier now because they thankful nerfed the fucking silence so you can dump your mana pool more often on DDD (which is the only thing I wish I had more SD for, honestly).
And if you get REALLY desperate, I also only run Sympathetic Healing 2 and just spam light healing from the Ranger. It actually keeps you up pretty well.