If the world is unpopulated, you can move your sim from house to house to test. As the game begins to populate the world, if there is a house you need to test that has a sim living there, you can move them to another lot that you have already tested. I suggest testing in a copy of the world, so the original remains sim free. if you change any lots you can save the new lot to the bin and then replace the one from the original world.
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@attuned - Thank you much for the guidance. The larger houses should be quick to check but I was a little concerned about some of the houses with smaller bathrooms. Using an active Sim to check on those will be best. So happy that I won't have to add 38 households to a test game I'll keep an untouched copy to use later when I'm ready to populate the town.