I'm guessing they mean a Boxster engine. A little more "ooomph!"
That's sorta what I was thinking, but the pictures in the ad clearly show a VW air-cooled engine.
I was wrong initially when I thought this sold last night in Louisville. What I was watching were the highlights from all of Mecum's auctions so far this year. This camper sold in Monterey in August of 2019. The boxer motor in this is just a boxer motor, not a Boxster motor.
And if you missed it in the description it is front wheel drive. The motor sits just behind the front seats in a little cabinet. The gauges are also from the 1955 356.
Jalopnik did a story about it earlier this year.