I actually use several Paul C. Buff White Lightning monolights that I bought years ago (they're built like tanks). I'd suggest the x1600 or x3200 for overpowering the sun (with the x1600 needing to be closer to the subject for the same effect). You can find them fairly inexpensively on eBay. Like the Einsteins, you'll need a battery pack like the Vagabond series, but one battery pack can power multiple devices with higher recycling times incurred with additional units.

If purchasing new, I really like the specs on the Godox AD600B Witstro TTL All-In-One and Godox AD600BM Witstro Manual. Considering that the battery's already included, the price comes in even less than a used PCB WL x1600 + new Vagabond Lithium mini, with the only downside being that the Godox's battery can only power one unit instead of multiple (more practically, two) lights.