Given that you are travelling perhaps look at this from another angle - If you have access to wire, (any wire), try adding more radials to the bottom (base) of the antenna on the earth side. This may reduce the common-mode currents from going back up the coax braid.
73 Ed DD5LP.
Edit: This sems to be an overlapping thread with
Feeding 1/4 wave vertical - how are you doing it? - Equipment / Antennas - SOTA Reflector
where also adding more radials has been suggested. I personally would try that first, before resorting to the choke. Length of radials - I like 3 metres long and 6 to 8 of them, but whatever you can manage… (I don’t “tune” the radials, rather just lay out a good coverage, on the ground, equally spaced over 360° around the base).