Replacement receptacles should be the same SCD type (SCD = self contained device) that was originally used. They have a plastic cover on the rear of them that covers exposed wiring. An outlet box is not required with these. They are designed to be installed in the thin exterior walls of an RV (typically around 1.5" thick).
As an EE, I can say that there is nothing inferior or cheap about an SCD receptacle in any way. They are specifically designed and CSA approved for use in RVs and mobile homes. Info. on the Hubbel Wirecon SCD is
here. The trick to installing an SCD is properly pushing the wires onto the IDC connectors. There is a special tool for this but it can be done by carefully pushing the wires in place with pliers or screwdriver. I've seen a few terrible SCD receptacle installations by an RV manufacturer with wires barely hanging on.
Standard residential receptacles can be used in interior walls or cabinets where there is sufficient depth for an outlet box. There is really no need to do this though unless you need the volume inside a box for splicing wires.
RV SCD receptacles (and switches) can be purchased at any RV vendor or online from many different sources. I would get a brand with a good industry reputation like Hubbell. Dyers for example, has one that is branded "Diamond". You can buy some residential receptacles that are worse quality than an RV SCD type... They all must meet CSA requirements and have a CSA marking on them though.