Given both arguments as to what constitutes an oval and looking to make it Figure 8.
Here is what I've come up with... whilst it's not a figure 8 but it does have the cross over element.
Please note the Diagram is not to scale, but if it were to be based on real track, In terms of corner Radius, the lower half of the circuit would be something akin to T4 the front straight (probably a bit longer) and T1 of the Milwaukee Mile set within the infield of T2 the back straight and T3 of Talladega.
The Start finish is on the Big Straight, the pit stop would take place during the Lap rather than at the end of a Lap.
A Lap...
The S/F straight would have some camber but the approach to T1 would be much like approaching T3 of Talladega, The Outer Banking is elevated, so coming off T2 as it would be, the camber equalises off from bith sides of the track, resulting in a gentle down hill over the bridge before the camber begins again for the banking into the Short corner of T3 and T4.
The short pit straight leads into T5 which is the tightest corner on the circuit, T6 Opens out but rather than the right hand side coming down (as banking normally would) the inside rises to level the the camber as the track then gently climbs uphill under the bridge before the right hand side of the track starts to camber up into T7 and then around into T8 before back over the S/F