To update this with a DP now that I've made the booking, in my case the rental company who posted the property on VRBO was the merchant on the CC charge, with VRBO showing up for the "service fee" portion, which was about 10% of the total booking charge. The actual VRBO charge showed up as "other services" so I couldn't use purchase eraser for that portion but fortunately the rental company charge coded as "lodging" so I was able to use purchase eraser for 90% of the total booking fee. I did ask them what their MCC was just to see what Cap One considers travel, but the rental company wouldn't tell me other than to say they were listed as "vacation rentals." In any event I've read that sometimes these merchants show up as Real Estate or Other Services, so YMMV. I also don't know if VRBO ever takes the full booking fee themselves or if the majority portion is always passed on to the property manager or owner directly. I'd be interested to hear if anyone else has experience with this for future reference, as well as how airbnb works.
I typically use the Chase Ultimate Reward portal to book hotels at 1.5c per point with my CSR (or transfer to Hyatt, etc directly), but started accruing Capital One Rewards Miles specifically for vacation rentals as there aren't many other ways to use points for those properties.