There are a number of lakes to the west of the sub-division. off of Highway 52. I don't know how close they are or what the terrain is like. I've been looking for some photos. One of these may have been in his mind. Or he may have wanted to get further from the house.
He had maybe three and a half (3 1/2) hours, at the most, from the time SW arrived home until he had to go to work. It would have taken at least an hour for the murder (s), load the car , drive to a location, and hide the car. I believe he would have needed a couple of hours to run home. So, yes, he may have had enough time, but it would have been close.
The children would have been dead about 4 or 5 hours if he murdered them before SW arrived home. Do we know that the dogs in the house were cadaver dogs? IIRC, it was only speculated. Also, LE referenced the smell of cleaning products in the house. Would that have mitigated the scent? You bring up some good points to ponder, but I don't want to ponder them right now. Just too difficult.