It's actually very easy to explore for slam. I start by using Ogust 2NT response. If partner rebids with 3NT (telling me they have a solid ♦ suit) I can continue to explore for slam using Gerber (4♣), any other rebid from partner and I sign off with 4♠. Of course if he rebids 3NT, it's not likely he will also be holding the A♥ or K♠ (or any other honor that could help me) because then he would likely hold too many HCP to be opening weak anyway. But none the less, the mechanism to explore is there. Worst case scenario by carrying on with Gerber to ask for kings is that you end up with a contract of 5♠ which is quite likely makeable if you end up being declarer and the opening lead comes from your left hand opponent. In fact, if you look at potential responses to Gerber (assuming partner does not have both aces - a reasonable assumption as explained above) then the only way partner can become declarer is if he responds 5♠ (indicating 2 kings) to your 5♣ king query -- in which case he has the necessary K♠ to consider at least small slam.