Fair enough. I'd probably use the Seeker as inspriration. Maybe a bigger hull without J-Drives?
Repulsors in Tractor mode are another consideration at higher TLs. TL13 gets you a Large Repulsor Bay, TL14 a Medium and TL15 a Small one, at 500tons, 100 tons and 50 tons respectively. Expensive kit, but potentially able to suck up everything nearby very quickly.
For the tug drones mentioned in High Guard, you're looking at a way to secure the tug against a big rock, then apply thrust to that rock. In that particular case tow cables and grapple arms are probably all that's required. Maybe use the docking clamp rules for the gear needed to secure a tug against it, to make it all one big object with thrust. Several tugs attached at different points would allow for a degree of maneuverability. As I suggested earlier, there's no rule that says the ship with the docking clamp has to be bigger than the thing it's clamping. The type V clamp doesn't list an upper tonnage limit either.
