We also have the 35 foot 50 amp OEM and we have a 25 foot extension cord. We also carry a 25 foot 30 amp extension cord and various dogbones. Like many others said, we have not needed to use the 25 foot 50 amp extension cord very many times. But when you need, you need it. We do use the 30 amp extension cord to plug in at home because our shed only has a 30 amp hookup.
We had our 50 amp extension cord made by our local RV tech. It is much lighter than the OEM cord and was much cheaper than purchasing a ready made extension cord.
One thing that has not been mentioned is that you get more power degradation with a longer length of 30 amp cord than you will with a 50 amp cord. If you must use a 30 amp cord, coil the excess cord length if possible.