Can the SRV tow multiple small objects if they are clustered together? Can we load a bunch of the smaller handheld boxes together to form a larger object and then grab them as a group?

That's certainly how I want to do it. The focus of the tractor beam is not a specific point. It's a sphere of influence. So if you get the things close together, then yes. But again, as we come to implement it, there may be some unforeseen technical reasons why it has to be a very specific point.