On a perfect build, the bevel would go through the exact inside edge of each side panel for their entire length.  The sheer clamps are epoxied on with the 1/4" offset so you will have material to bevel/cut off to provide a large gluing surface when you attach the deck.  You need the 1/4" offset near the center of the hull, where the bevel is the most slanted, not at each end.  So you'll be cutting most of the sheer clamps off near the ends.  But you shouldn't need to cut into the side panels as much as 1/4" near the middle of your hull where the beam is widest.  More like an 1/8" or less.  Try to keep the curves of the sheer clamps, both fore-n-aft and side-to-side, as fair as possible so you have a good surface for the deck to attach to.  Good luck.

Hector,

While planing my Chese 17LT I noticed I was planing quite a ways into the side wood (although I don't recall the exact distance).  But if you've cut yourself a guide (for fore and aft curves) you can get a safe, comforting feel for how far down to plane all along the boat length.  Yes, you'll have to plane the ends (fore and aft) flush because the deck is nearly flat the last 12 or so inches of the boat.  I didn't go down that far and wound up filling the cracks (so to speak) with thickened epoxy to give me a smooth surface.  Don't sweat it, though, sounds like it's coming along great.  You'll understand it all when you nail the deck on... all that planing will suddenly make perfect sense.

Good luck; post pictures if you can,

Larry

Just finish sheer planing on a Chese 16 and also planed into the side wood near the middle of the boat. I had to in order to have a smooth curve from the side walls into the deck beam. That does mean, however, that you'll have a compound curve to the forward deck when putting it on (not only does it curve across the 16" radius, it also has to curve a bit up from mid to bow).

Other's experiences?

Eric

I like to preserve the top outside edges of the side panels as reference lines for the finished sheer line of the boat.  They're already nice eye-sweet curves, so I think it's easier to just not cut into them. 

Those are the references I use while checking for hull twist too, because then I don't have to be so careful that my sheer clamps are at exactly at the same height above those edges on both sides of the boat.  I tape two little same thickness "elevator blocks" to the bottoms of my winding sticks so they ride on the tops of the side panels, instead of on the sheer clamps.

Since I don't cut into the side panels, I often I find that there's not quite enough extra "meat" on the sheer clamps near the forward half of the cockpit, where the edges of the deck are so steep.  If the gap between the inside edges of the sheer clamps and the deck will be significant, I glue on an extra strip of wood and plane it down to accept the deck.  If the gap will be a small one, I just fill it with thickened epoxy.