Please post data to support your claim that it is crossover voters that allowed a Trump win in SC.
Trump won among republicans with 32%. This made up 76% of the primary vote. In a closed primary he would have won.
Trump won among independents with 33%. Rubio was second among independent voters, that is largely where he passed Cruz. Ind did more to help Rubio than they did Trump. Ind were 22% of the primary vote.
Registered dems made up only 2% of the GOP primary and didt not affect who won. They may have influenced some of the down ballot positioning.
Analysis of the actual numbers shows the dem vote did not affect the final SC results.
If you have actual hard data to the contrary please ping me.
The CNN exit poll says Republicans voted Trump/Cruz/Rubio 32/24/23.
I have no hard data at the current time, but I expect some will be along eventually.