i have a rifle that has been in one 3 years with no issue
and I have a rifle that spent 9-12 months in a case years ago that has the texture of the lining imbedded in the stock
the primary issue for the gun is that the oil or preservative you use doesn't eat the foam in the case and cause it to stick to the rifle
my dads shotgun lived in the case in the closet for about 17 years he would clean it and put it away after deer season and it was late October early November when he took it out again never an issue the house was climate controlled heat and A/C just a soft case I think he used 1in 3 oil so nothing special. he bough a safe when I was about 15 because my little brother was having freinds over to the house and times were changing and we had added a few guns to his one shotgun
we went just a metal safe no fire protection just a good lock it weighed maybe 70-80 pounds it will deter who it will denture and who-ever was determined can open one of the big fire safes the weight is nearly all in the fire protection not the steel
the Hornady 1 shot seems to do fine with this not melting the case and rust prevention , I don't recall what I was using years ago when my rifle had the case stick to it that would have been the year before he bought the safe
so make sure totally dry , use something like hornady one shot drylube and cleaner and store away checking every 3 months ND isn't particularly humid and especially if your trailer is air conditioned in those hot summer days
that or the metal cabinets work fine and keep hand off that should not be on them
https://stack-on.com/product/8-gun-security-cabinet/they only way maybe 30 pounds so noo need to reinforce the floor under these
obviously theft being the biggest issue a cabinet fastened to the wall is best
hard cases will certainly work as long as they are completely dried off after use and not melting he foam can be avoided
cables through the locks would add a layer of slow down to theft but not a big one