All our previous campers were 30 amp and I have several 30 amp extension cords, enough to reach 120 feet. 2 - One 50 footer and three 25 footers.
When we got the 5er last September, it was 50 amp. So, I made sure I had the 30 to 50 amp adapter (dogbone) in the event I ever had to reach longer than my 50 amp cord could go. I've used the dogbone adapter a couple times, not because of distance, but because the campsite was not a 50 amp. I've not tried using the original 30 amp cords yet. So far, everywhere we've been the 50 amp has reached.
The only thing when using the 30 amp service, is the fact we have to revert back to carefully monitoring power management in the 5er. A few simple steps and we've never had any problems, just like in the 30 amp travel trailers we had. Step 1: flip the water heater to gas an off electric. Step 2: run only 1 air conditioner. Step 3: if running the microwave, turn off the air conditioner first. Step 4: If using an electric skillet or an electric griddle, plug into shore power with a 15/20 amp extension cord and just don't plug into the camper. These steps work well when using 30 amp. But we sure do enjoy the 50 amp and not having to monitor what we are doing.
So, meanwhile, I still carry all that 30 amp cord with us. We just never know when we'll be in a campsite that's designed very different. In Indiana, the unexpected is the expected!
Someday, I hope to acquire a 50 amp extension cord. But I'm not willing to pay the bucks for one yet. I hoping I may find one at a yard sale or garage sale someday.