Wow, talk about overthinking things. Pull any one of your 12vdc switches out and look at the back/side. I guarantee that they are rated in AC, not DC. There is no appreciable difference in the contacts of a household 120VAC switch and an automotive rocker switch, other than perhaps the size (household switch contacts will be larger).
The only way a DC current will "weld" contacts together is if the current is higher than the contacts are rated for; AC or DC makes no difference. 6A at 120VAC is equivalent to 60A at 12vdc.
Personally, I think household switches in an RV (along with the requisite cover plate) would be extremely ugly, but to each his own.
