No you're not crazy at all. Lots of us here have considered possibilities along these lines and they are still as plausible as the morbid speculation that has gone on regarding KC being the murderer. Even on national TV they simply run wild with speculation, creating a whole speculative persona for KC along with motivations, etc. It's really unbelievable. Not that I can rule KC out at this point, but the speculation stated over and over as fact night after night on TV is pretty disturbing.
Lots of us have thought it's possible Caylee was held due to KC's involvement in a crime or because of KC witnessing something or even Caylee witnessing something. Casey may have thought friends had taken Caylee but was mistaken. Or, she may have known who had her and may have thought, however naively, that Caylee would not be harmed. She might not have been able to pay back money she'd taken, or she may have made off with someone else's drugs and sold them, or she may have crossed the wrong person or people. She may have been involved in a crime that went wrong and someone was murdered, and this was retribution, or it was in order to silence KC, many have commented on the gang hand gestures in the many photos (which could be completely innocent of course). KC of course could have been threatened that Caylee would be killed if she told, or she might have been thinking she was going to get her back somehow. I also did wonder about the possibility of a scam involving a faked kidnapping, either to get attention or money in some way, and it going wrong. One theory I can't see is the one you hear about Caylee dying in an accident but then KC staging it to appear like a kidnapping or murder, too much risk of incriminating herself in a murder. But the rest, certainly possible.
Regarding the heart and tape: I definitely think if KC was the murderer, she would have removed the tape before disposing of the body, just in case the body was ever found. Even if she had found Caylee's murdered body and disposed of it in a panic, one of the theories some of us have discussed a lot here and I still think it's an interesting theory, I think she would have most likely removed the tape from Caylee's face before disposing of her. So the fact the tape was left on is very odd, too incriminating to leave the body like that if she was the murderer, unusual for her to have left the body like that if she wasn't the murderer.
In either case though, I could easily see KC wrapping her in the blanket, whether for purely practical reasons as another poster mentioned above, which could certainly be the case, or for a more emotional reason. And I could definitely see her putting a heart on Caylee's hand or cheek, but not leaving the tape on and putting a heart over it. (In the case of finding Caylee's body, I think KC would probably have called the authorities instead, but you never know, if she was threatened or if there was a note that said this will happen to you too if you talk or if you don't pay us back our money, or whatever.)
The tape left on and heart placed on it seems more like a hate crime by another perpetrator, the heart could be a detail that a pedophile enjoyed, or could be a kind of calling card used by the killer.