Hi Nicole!
You have asked a great question and one that has stumped a few of us. Normally getting to an early dining reservation is simple in answer as the best way is via taxi. However, with you having an ECV, a wheelchair, and a stroller it becomes more difficult. The wheelchairs and strollers are easy enough as they can be folded and put into trunks of cars and vans that the Taxi service might offer. During regular day hours using the Disney bus transportation is best bet for all three pieces as they can accommodate ECV's easily.
Early morning dining reservations are tricky for all guests and not just those with the implements as you will be traveling with. Sometimes you can catch an early bus to a park that has Extra Magic Hours and then transfer to the resort where your dining is located. You did not mention a specific date for me to check on what park, if any, might have those extra hours to see if that would be possible. Sometimes you can get on these early buses and let the driver know where you need to go and after they make the park stop they can take you there but this all depends on time of year and their scheduling.
I feel the best and most guaranteed transportation for you would be to contact the Mears Company to discuss what options you have to reserve a vehicle that can handle your needs. That number is 407-422-4561. You would only need it to get to the breakfast as you can easily use the
Disney Transportation from that point on.
You can also call the Disney taxi service, 407-422-2222, as there is a chance they will have a couple of cabs that can accommodate the ECV as well as the other two things.
Most services are not allowed into the resort loops so you would have to take the internal bus to reach the front area. You definitely asked a tough one with no simple solution.