Don't worry too much about the jacks/rams being exposed to weather...
I have had anywhere from 2-4 mid-size tractors on my place in NE Nevada and they sit outdoors 365 days/year.....Rams exposed, or a part of each ram exposed year round.......Never a seal issue ......And never did any preventative maint on the rams.....
Now--that said----I do rub down the rams on my MH with ATF on occasion....And it sits indoors in a climate controlled barn when not on the road.....I don't think this is necessary and I don't even know why I do it.....!!!
Steve and Liz
Elko, Nv and SoCal
2014 Dutch Star 4018