Please help! Is this buyer of my trailer trying to scam me?

So they wrote the Cashiers Check for more than what you are selling it for?

Say it costs $1,000 for shipping, that is what they wrote it for in addition to sales price.

It is a scam. The "shipping company" shows up, YOU give the "shipping company" the $1,000 cash (as he said, they only ship with cash).

You are now out your $1,000 cash and your RV and the Cashiers Check will not clear.

And who do you sign the Title over to? They should be present to sign it.