I use Grip Clips
to make panel tie outs on a tarp wherever I need them. They will slip on silnylon in some situations, but for the most part I have been very pleased with their performance.
I really think side or panel pull outs are a great feature to have on a tarp, but you rarely see tarps with them included. warbonnet guy is going to include them on his Super Fly tarp when they become available. There is a thread
that talks about attachment methods