There's anecdotal evidence that exposure to UV can damage the eyes of Corns lacking black pigment, so yes, that could theoretically be a risk to your Amel.
Plus if she's outside, how are you going to provide a "cool spot" of the correct temperature, so she can cool down if she needs to? And if you manage to get a cool area for her, how will you know if she needs to use it?
And what if you come across someone who has a phobia about snakes? If they decide to lash out when caught unawares (because phobias can make people act in a very instinctive and irrational way), both you and your Corn could be in danger.
I can't really see how taking a Corn to the beach would be of benefit to it. As you say, sand is a bad idea for Corns - and as any human knows, all you have to do is LOOK at a beach and the darn stuff gets everywhere! :rofl: Plus the unregulated heat will be a problem and UV may a potential issue. Personally I wouldn't risk it.