a suggestion would be to do chin ups--always a poll about [scaffolding,etc...]. carrying heavy
luggage whilst traveling, could be good. biceps get alot from lugging--like grunt work on manual
labor. hand grips alone, i'd think you'll feel strength where it's best to feel it...at the ends of your
arms [the usual weak link in the average muscle bound bloke and the reason i stopped lifting as
much...desire heavy handedness over powerful guns/biceps].
in my humble opinion--to surmize: chin ups [palm toward face]--if you wish to feel that arm
strength thing, otherwise you will lose strength but not so it's a detriment to fighting, if you
ask me.
when i travel, i find something to slap [not kidding]; open handed hitting can be possible in many
places--from the corner of two adjoining walls; to a wooden squared pole [pillar]; to a tree...my
hand and arm strength feels like it's a working practical strength, and my fore arms and hand
strength slowly increases steadily over time. possibly not what you're looking for, but there it is.
good luck and safe travels