OK unless you are REALLY good on roller blades (and we're talking able to leap off ramps and stuff at skateparks type good)
I would not even think about roller blades. Way too dangerous.
Scooters are safer, when used with proper bikejoring attachments and a back and front set of proper brakes.
Cycles (Mountainbikes ideally) either with bikejoring attachments or a Springer or Walkydog attachment even better.
Then onto Rigs (like a scooter but 3 or more wheels).
Anything that needs the bikejoring attachment your dog(s) are going to be out front and need to learn the proper commands for left / right and stop.
There are plenty of experienced mushers here, who will be able to give you the nitty gritty technical info.
However this should give you somethings to think about.