I don't think it's cheating at all. People have been doing this since the 50's. Except they would build their models by hand and take pictures. Alice in wonderland did this (even used a real human model for Alice), Lady and the Tramp did this too.
I do this as well, except I use sketchup. I keep telling myself "okay I built the model myself, which also takes a lot of time and prep for, so I should be able to use it however I want."
If you want to feel less guilty, and only need background help,I would recommend sketchup instead of sims. You get more camera angle control, you can save the models for future reference, it takes up less space on your computer than a sims game, and it absolves a lot of the guilt. Plus if you're super lazy, you can import props like TV's computers and the like from the community.
tldr: Keep doing you, these things are tolls made the be used, might as well use them.