Spray basting with 505 is my favorite way to layer a quilt -- very fast. Just be sure to spread a large flat sheet out first to catch any overspray. If you do a search on spray basting, you will find lots of info and tips.
Instead of SID, why not use your walking foot to make curvey lines across the quilt? It's a lot easier than SID because you don't have to keep your eyes glued to that ditch. If you're a little bit off nobody knows because the lines aren't supposed to be straight lines. You can do these lines in one direction only, or in two directions to create cross-hatching. You can do the lines across and down, or from corner-to-corner. You can echo-quilt the curving lines or make every line different.
p.s. That is a *very* cute quilt!!!