The reasons I am thinking of for doing this are 1) the push-in cord takes up a lot of wasted space in the enclosure behind the dinette bench, 2) I would like to install a surge protector and there really isn't another decent location for it other than the space the cord is in now, 3) the existing cord gets quite stiff the colder it gets out and is harder to manhandle back into the enclosure 4) the Marinco cordsets have fine-stranded conductors and are much more flexible, as is the insulation type and thus it coils up fairly tightly, 5) by using a detachable cord, the existing cord enclosure can be used for storing other things like spare tools that don't get used much.
I've also just installed a 15A inlet and a receptacle by the kitchen counter. Now we need space to store the 15A cord.
I've looked at buying a Marinco conversion kit but I can buy a new Marinco cordset and inlet for the same amount or less than the kit costs. At first I thought I could just buy an inlet and a female connector and re-use the old cable, but just the connectors are like $50 each including the weatherproof boot. This is a frustrating math exercise to be sure.
Regarding theft concerns, it seems like no matter what, you are at some level of risk. I thought about putting the receptacle behind a locking hatch cover but that turned to be too expensive anyway. I'd at the least want to have a 30 - 15 amp pigtail adapter so we could use a 15 amp cord temporarily if the 30A cord got swiped.
When we have the 30A and 15A cords running at the same time, theoretically, I could design a circuit that sets off an alarm if one cord was not pulled out or cut at exactly
the same time (within milliseconds) as the other. The only way for anyone else to prevent the alarm going off would be under a site power failure then stealing the cable(s). However, I digress a bit on this and am guessing it would just be cheaper and easier to have a spare cable handy.
On dimensions, it *looks* like what you do is retain the mouse hole cover and remove it's lid. The inside dimension of our mouse hole is 3 1/4" which coordinates with the Marinco outer diameter. The Marinco support info. is vague on the details. So I think I am going to get a countered model and take it from there.
This is a photo of our mouse hole.