Try listening for the Carolina Beach (Wilmington) Viper site ... The control frequency is 868.8875, and the site ID is C508-0007.
This is the site to the east of Bolivia.
I logged the Carolina Beach site the Sunday before this past (on 04/15) while poolside at the Surfside Beach Resort. The pool is at ground level on the south side of the 8-story hotel, with no other tall structures to provide signal reflection.
BTW - here's the antenna I was using on a 396xt that trip:
OPEK HR-25 - Dual Band VHF/UHF Stubby Antenna 144-148 & 430-450 MHz
I knew I had locked onto a Viper site at the time, but didn't know which one. Once I had a chance to match the site ID on RadioReference, I figured the signal had been enhanced by a pathway that was mostly over water, as well as a cold front that was moving into the region.