Another option you might want to consider is a keyless entry system, RV lock Co. make several types, we opted for a keyless with keypad and FOB, much like an auto (and it also has a key). Cost for the top line was $250 but what is the cost of security? The factory installed locks are just junk and really not very good with so many being keyed alike. An example is the storage door keys (#751s) that are standard on so many RV's. Anyone who has a 751 key can open another persons RV that also uses a 751 storage door key. It took me 30 minutes to install and program and we feel much more secure as we keep our unit on site for 8 weeks a year for a weekend program and we also NEVER worry about forgetting the key at home as we can use the keypad to gain entry.
2008 Dodge Ram 4X4 Quad cab LB 2500 Cummins 6.7L TD / 2013 Columbus 320rs. Camped 50 days in 2015. RIP Angel the camping Cat, we will miss you.