There might be some psychology involved on the client side. They get drawn to base price that seems cheap, and then get upset when there's a carcass fee (especially if it's high).
Personally I prefer transparent price structure (including tipping, coming from a culture where customary tipping is seen as strange). All the better if price structure is also optional and built to mirror the success rate. I.e. low base price, shot fee, trophy fee, carcass fee. That said, the whole structure should present good value, and build upon itself. And enable true option for choice, if you don't want trophy it should be fine, if you can only afford "presentative" trophy (instead of medal) it should be fine, if you don't want multiple cull animals with price tag it should be fine and so on.
One extra note, if client takes the carcass it could be more work or at least time spent for the stalker. Need to skin, break the carcass, more cleaning on the premises, or just spend time when client is faffing about. So that should be factored in to be fair to the stalker.