I have been a sea and freshwater angler for more years than I like to admit, and can say without any worries that your carp rod will be perfectly OK for fishing in the sea provided that you use it sensibly, I use a 3lb tc Carp rod for Bass, and have had them to 6lb from the beach, with no problems at all, and I use the Carp rod in preference to my Bass rods as it is lighter and more pleasant in use.I use the same rod for float fishing for Bass for feathering for mackerel, deep spinning for Pollock off the rocks (so far my biggest rock caught Pollack is 9-1/2 lbs .... on a Carp Rod ) and also for light bottom fishing for flatties.
Yes I also use my ZZiplex / Conoflex and other brand name rods for specific purposeseg, Smoothhound, Cod etc, , but if you are only going sea fishing occasionally then dont waste your cash on an outfit that may stand in a cupboard for 11 out of 12 months of the year.
I use a Shimano 3500b Baitrunner reel loaded with 30lb Power Pro braid with the Carp rod, it performs extremely well, and was in fact designed as a salt water reel , though these days they are used more for Barbel fishing and spinning than in salt water.
Go for it.......... best of luck.....
Dave