Pretty sure Exit is only if theres an emergency then its thru the roof or side escape hatch. I guess ours is 'Rear' entry, if it were Back or Front door means I have another door, somewhere-haven't found it yet. Dont want any one climbing out the hatch, suppose I should glue on one of those large stickers over our Door.
Not familiar with the Palomino Mini L, possibly 2 doors? As this is on poptop maybe an All Door.
When you were at local RV didnt have replacement locks you could look at? If unlocked (I assume) remove and take with you or to locksmith. Have you tried your baggage door keys, a few use same key? Or add a simple dead bolt. Due to age replacing probably a good thing if you get fit.
Could contact mfg
http://palominorv.com/ContactUs/ for recommendation for key or replacement lock that would fit.