Well, if you're done pulling the wings off, why not go ahead and put the close tolerance bolts in and torque 'em down? What's the downside to putting all of the correct bolts in? Maybe I'm leaning to the side of caution, but I would want ALL of the bolts that hold the wings on if the fuel lines are connected for an engine run. True, if you're just doing a run-up, there's really not much strain on those connections and you could do what you wanted. But if the ground-down hardware store bolts don't have nuts, your connection to the spars isn't as Van's designed and you could potentially have an unintended bending moment around that connection.
Just a thought, but why not wait until everything is about ready to fly, then perform an all up test with all of the connections finalized? After all, you're not going to have to pull the wings if the engine doesn't start. Just make sure you have the nut plates installed on the bottom fuselage skin before calling it a day. But I'm assuming you've got those in and have drilled the rear spar holes in accordance with the instructions.
And yes, check with your insurance carrier to see how they define "not in motion" (builder's insurance) versus in motion or an airworthy aircraft. First engine runs are memorable events, and usually for all the right reasons. But in the unlikely event that something goes south, you want to make sure the insurance has your back.