Monte Carlo simulations of the interior structures that are compatible within 3σ with the observed planetary radius (dashed green vertical line; the shaded green area include radii within 1σ of the best-fit value) and planetary mass in the solution with 2 GP quasi-periodic kernels, when their uncertainties and the uncertainty on the stellar age are taken into account. Fitting the planetary radius in the case of enhanced opacity of the envelope requires large cores in excess of 30 M_⊕, while the faster contraction of envelopes with solar opacity allows for smaller cores compatible with the mass range estimated for Saturn.