We had DS1 in the middle while DS2 was in the capsule & he couldn't reach to harm the baby, although I guess he could have thrown toys at him. We moved DS1 to behind the driver when we got a new seat for him & rear faced the old one when we returned the capsule. Having rear facing behind the passanger makes it easier to loosen the top strap to get baby out rather than behind driver.

I very rarely parallel park, most places I go to have off street parking, or on street that's 90 degrees to the kerb so DS1 getting out on the footpath isn't a big concern to me.