In case you were not aware: not only is CNG difficult to obtain as a cruiser, but the amount of fuel
contained in a tank is vastly less than an equivalent sized LPG tank. Reason,of course, is that the CNG while compressed is still a gas, while LPG (liquid petroleum gas) is, well, a liquid and far denser.
aspect of CNG is attractive, but the practicalities rule
it out for cruising beyond local waters.
However, converting burners isn't difficult, and most manufacturers offer the correct sized jets for LPG.