It is definitely possible to paddle a sit-inside tandem kayak or one with molded-in seats by yourself, but you will have to pick whether you feel more comfortable sitting in the front or back seat.
Can one person use a tandem?
First, tandem kayaks are made for two people. If a person runs it, he will not be able to control it properly, he will have to face various problems to control it. ... There are many seat-on-top kayaks with extra seats in the middle so you can easily control it while sitting in the middle.