How much of the fruit do you cover with cloves?

Keep in mind that clove oil is an analgesic. It's an old remedy for a tooth ache and used to be used in temporary fillings. More is NOT better, as the cloves will literally numb your tongue if used in large amounts.

Cloves are very strong in taste. I would use them sparingly.

It depends on how much you like the taste of cloves.
The recipe says 1-2 tablespoons total cloves, which would give half to 1 tablespoon for each fruit (one orange, one pear).
As with other strong flavors, it's harder to compensate for too much, and always easier to add more.
Maybe start with 1 teaspoon clove per fruit. Then after cooking, taste. If you want more clove flavor, add some more and simmer.
Good luck with your results.