Delta's are somewhat forgiving, the main problem with changing the design is that the tow point, which is normally fixed on a delta, may change. You could design the keel so you can alter the tow point slightly to compensate, but if you compare multiple plans you'll find tow points and keel designs are all over the place too. The most important aspect is that the kite is symmetrical side to side, I always leave extra fabric while working on the panels, then fold the sail in half along the spine line and cut the final outline so both sides match perfectly, you're on the right track there.
Don't use Super Glue, if you're using Polyester fabric Scotch 9460 tape will hold it together better since it remains flexible. If using Nylon fabric then the C3 Sail Tape will serve the same purpose. If it's Silicon coated fabric all options except sewing are off the table. These tapes are used on racing sailboat sails without sewing, they'll hold up fine on a medium sized SLK. You will need to stitch the spreader pockets though if you make them like that plan, there is simply not enough area in relation to the stress to achieve a reliable bonding. Why not use APA leading edge connectors? I've done so on a few delta type kites and there are commercial examples too.
Avia 1880 (.188") pultruded tubes would be a better substitution for 9mm hardwood dowels but solid fiberglass will work too. I don't have any stiffness specs on solid fiberglass so I can't compare the stiffness, my guess is 4mm would be more flexible then 9mm hardwood, it will work but the high end wind range may suffer.
Hope you enjoy the project.
