Dave, good choice to try to learn to cook spares with no foil. Lots of folks turn out great spares that way, particularly on charcoal smokers that use water pans.
One BIG tip though is to start with the best meaty and decently marbled unenhanced spares you can find, with the best 'round here are at Sam's Club, and they have the brisket bone removed. I search through the three-packs for weights in the 13-15 lb. range, and just look for the best slabs. It's always a gamble since you can't see the middle slab, but the brand our Sam's is carrying now is head and shoulders over the ribs I've used in the past like Smithfield.
Use a decent amount of sugar in your rub, my preference being brown or even dark brown and cook evenly in the water smoker at 235-250* until tender. No mopping or spritzing.
I'm sure I'm repeating myself here, but my last two rib cooks have been as good as any ever, and it's as simple as it gets. I'm leaving the vents wide open long enough to know I'm gonna get the temp up to 250 or close to it asap. None of that 225* stuff for me on a water smoker for ribs or chicken since I want the water really simmering good, and you want some surface texture to develop before the ribs get tender. Can't stress enough how you'll get better slabs if you keep the ends out the outer hot zone, either. Burnt ends belong on briskets, and the 1/2 slabs in my six slot rack has just worked FANTASTIC for me last two cooks. Just trying to help you out, and wish you could've tasted 'em!
It's really that simple, and if you want to remove the variable of saucing at the end, try some Memphis dry ribs like Chris Lilly's recipe. That's my favorite technique anyway, hands down. Hope some or all of this helps!