YBP, in describing the stock wheels as "thinner," I presume you're talking about the width? If so, that's one reason I've not yet done any suspension mods on my car. I'd want to do wheels at the same time, and that means tires too, and all that adds up to a big bottom line.
Yup. Width. The stock wheels seem to get sucked into the frame when the car's lowered. I agree that suspension (~$1000) and wheels/tires ($$$$-depending on what you want) are a huge expense. However, I knew I was going to spend the cash, before I received the car; based on my previous mustang and other cars I've modded.
So far--and I've dumped some cash into this ride--suspension is by far the best thing for me personally. That includes a tune. I know many drag strip guys want the power, but as an old guy who doesn't hit the strip any more, the suspension was more important for me. I knew just by looking at pictures of a 2011 5.0 I would drop it and get rid of the 4x4 wheel gap. While I was waiting for the car to show up I already had parts waiting in the garage. *Kids had to eat peanut butter for a few months, but hey, they got over it...
BTW, I'm very glad to see more women choosing a V8 nowadays. It's refreshing!