Nice, I made one recently with an old tire. Best piece of equipment ever IMO. Im doing almost the exact same plan as you. I try to do it 3x per week and am doing 6 x 100ft each session. I start with 90 seconds between reps and every session or every other session decrease the rest by 15 seconds, until I get down to 30-45 seconds rest.
Great piece of equipment, can be used for strength, conditioning, or recovery.
Right now im doing 130lbs for pushing, and 65 for pulling for only 60ft. But im using a car tire, on a rocky asphalt, so I dont know really how this would compare to a metal sled. And I just have it hooked up with some nice rope, and 2-3" thick PVC handles.
All in all, it costs like $20 and is definately the best piece of equipment for the price. Only problem is that you need weight to add, and im already maxed out. Im hoping to get a large truck tire, and then I can progress further.
Do you guys have any specific goals for sled work? Im just getting into it, but I want to do all my weight down my street and back for time. (Im guessing this would be about 200-300m) And then eventually i want to go for REAL distance, like 1/4mile, 1/2mile, and mile.