I'm 62 and have been stopped maybe a half dozen times in my entire 47 years of driving. I've NEVER been worried or even asked to get out of my car and for dang sure never had my person searched. If you are truly worried about this, you have major issues.
I bought car 2 years ago for CASH in another state. $12,500, No issue. He did let us drive back with his tag and we mailed it back, and yes I did get insurance on it before we left for the purchase.
I've bought 2 lasers from China in past 4 years, wire transfers which for overseas are $60 each. Way east and safe.
I did buy a $23,000 car last year from dealer in MO, 150 miles from home. Used Cashier's check. The dealer wanted a photo of it the day before. No issues. I asked and they said Cashier's check worked for them....
But wire transfer would be safest, especially from someone out of the area.