I've always just used one of these clips.
However, I position the clip away from all the edges that the seatbelts encounter. It usually ends up in the middle of the seat.
Preset the length to "too short to clip in" then weight the seat to force the seatbelt to click in.
Also, as mentioned, pull the belt out all the way to put it in childseat mode.
I've got two kids, and had two child seats in the middle row. Now it's one childseat and one booster on the other side.
For top anchors, if you're not running the 3rd row you can clip a forward facing seat top anchor in to the floor brace that the 3rd row clips into.

However, I position the clip away from all the edges that the seatbelts encounter. It usually ends up in the middle of the seat.
Preset the length to "too short to clip in" then weight the seat to force the seatbelt to click in.
Also, as mentioned, pull the belt out all the way to put it in childseat mode.
I've got two kids, and had two child seats in the middle row. Now it's one childseat and one booster on the other side.
For top anchors, if you're not running the 3rd row you can clip a forward facing seat top anchor in to the floor brace that the 3rd row clips into.