It happened several times on my pre-Tiger way out in the boonies in the pre-cellphone era. The first time I was totally surprised, being fairly new to both the RV and to dirt road exploring. My hammer was no help. Two guys working on the nearby phone lines rescued me. They discussed possible solutions, then deflated one tire, got the rock out, and reinflated the tire with their compressor.
After that, I carried a pry bar. Even though that plus the hammer usually did the job, it often took quite a while. And RichieC is correct, there often is not enough room down there to swing the hammer.
And now you know why I bought my SRW Tiger.