The other option is to use what UP supplied in their Cupola Seats, Seat Belts.
Most of the earlier cabooses (CA-3 up to about the CA-8) had the "Lay Down" cupola seats. The Bay Windows had seats with seat belts. The ex-Rock Island cabooses as well as the C&NW bay window cabooses had no seat belts but there was plenty of evidence from where the paint was worn away on the walls that the trainmen would brace themselves. I have also seen the "Lay Down" seats in Conrail cupola cabooses as well (Yes, we used some of those on through trains or assigned coal trains). The more modern "saddlebag" cabooses, used by the D&RGW and the BN had walkover seats placed in the middle of the cupola.
Slack action was something that all good engineers tried to avoid, usually using air and keeping the train stretched through sloughs where the train was known to run in. Rear Brakemen were required to give roll-bys from the back platform of the caboose when meeting another train. This was particularly harrowing while passing another train on a double track main line at 70 miles per hour. Walking from the Cupola to the Back door could be a real hazard. Yes, it was required, even in the winter, on the fly.
There were overhead rails to hang on to in our (UP) cabooses when you walked to help mitigate the effects of slack action that could throw you on your butt or back to the opposite end of the caboose, or worse, run you into a hot stove. They saved me more than once.
This was not a problem for the 3' gauge that I know of, but slack action, however slight, is still a hazard, it can throw you on the floor or knock out your teeth on the seat opposite. I would bet dollars to doughnuts that most trainmen kept themselves braced by using the back of the seat opposite of where they were sitting, unless they had put a walkover seat in the cupola and then you would brace your feet against the wall. On UP we had small foot braces that looked like two rung ladders attached to the wall in front of the seats as well.
When the new generation management came along and insisted that "Power Braking" was using too much fuel and had to be stopped in favor of 100% Dynamic Braking, the slack action problem came back. After the end of the brakemen in the wholesale slaughter of jobs in the 1980's, The use of FRED eliminated the cabooses and the slack action injury problem went away.
