Here are the major polls and expert statistical analyses estimating the number of libertarians in the US.
These surveys and models were created in 2015 or earlier. A few of them occurred during a period of peak libertarian visibility. Yet they span about a decade and, during that whole time, they constantly confirm a large, stable libertarian base, which we suspect continues to exist. Decades of Nolan Chart quiz data echo these findings. Even at the lowest estimates, tens of millions of Americans are political allies.
The message is clear: libertarians already exist in huge numbers. The most important strategy is to find them.