Lightest slider hitch?

I'm not to familiar with the Ram Mega Cab, but I don't think you need to worry about hitch weight. Your issue is, like most, payload capacity. With a SRW and wanting to haul a toy hauler you are going to have limitations anyway. If you are worried about a 200-300 lb hitch vs a 100 lb hitch, then you might be looking at too big of trailer. You can add too much weight to the trailer by throwing in some more stuff or adding firewood to the bed of the truck or something. One of the posts mentions a 3500 payload capacity. So, as long as the trailer you are looking at isn't coming close to that payload, then the weight of the hitch isn't an issue. You should get the hitch that fits your needs and truck trailer usage not shop by weight. I would consider an Anderson if I didn't already have a B&W but simply because I have both a 5th Wheel and Gooseneck Trailers. If I didn't have both, the 5th Wheel hitch would be all I would need.

Just make sure the trailer pin weight isn't pushing the limitations of your truck and you shouldn't have to think about it. But, also remember, those numbers are not struck in stone. Some will feel the truck is overwhelmed even if the trailer isn't close to the actual number on paper, and others will feel they can go hundreds of pounds over that number. Just depends on the person, where you are driving, and your experience.

Good Luck