actual / simple jungle solution

Upon clearing 35 or so camps/scuttle drag or baron cleared(from very get go of game, selling jungle item restores your champion summoner spells (thereby replacing smite).

Or maybe keep smite without enchantment. The smite icon would be placed above trinket icon. Its new default usage key would be 8. so a new 7th slot that you can be drag/dropped into any of the other slots to change key its assigned to. Swap its place with whatever other item was in say slot 1 or 2.

This way late game when you no longer need smite necessarily, you can have a summoner spell without a jungle item.

You'd have to pick your summoner before the game start, it will list it as greyed out/disabled summoner at the start to indicate what you'll have for late game.

jungle items could be sold at a discount as well, little to no penalty, just make sure you cleared 35 camps. youll be notified when you can if you so choose.