There are two possible 'solutions' to the perceived Camel Problem:
1. Nerf Camels. Maybe something as simple as making them give only 2 instead of 3 resource slots, of which they occupy one. BUT that is going to make getting the total required Resources slotted much, much harder.
2. Have a 'Camel equivalent' Building or Quarter that gives 1 - 2 extra resource slots to the city.
Right now, I believe in the Modern Age (which is the potential Camel Problem age) only the Port structure gives any Resource increase, of 2 in that city. But of course, that structure is only available to coastal/navigable river cities.
More general Modern Age structures that could legitimately add Resource slots might be the Factory, Rail Station/Yard, Department Store, or Stock Exchange (that last representing the extra monetarization of resources). Any or all of these, of course, would still require more effort to equal the Slotted Camel resource bonus, but even at +2 Resource slot/structure you'd only need one of each to equal the 4 Camel Capital mentioned.
Another point to mention in this regard, right now to max the Resources using Camels practically requires you to seek out desert or 'semi-desert' positions for at least one or some of your cities. To some extent, that makes the Camel mechanic terrain-dependent: if you start as Catherine with a Tundra bias, Camels are not likely to be your neighbors. Hatshepset or Xerxes on the other hand, are quite likely to be given a bonus to the economic game from their desert start bias and the increased Camel Likelihood connected with it - which, by I suspect no coincidence, matches the Economic attribute all of their Personas share. Providing a Camel-Alternative in Antiquity and/or Exploration removes that bias/bonus, which may or may not be what the game design intended . . .