I'm glad that you enjoyed it! And thank you for the wishlist! <3
I actually KINDA have something like that already. For completing a Field's objective, you get its special Cargo ("Field Relic") that you can then pack into your truck. And I plan for those Field Relics to have some modifiers/mechanics from the Field they came from.
For example, Overgrown Field's Relic lets you spawn those Overgrown grass/resource caches on any other Field. Of course, it won't carry over the full Field mechanic (you won't have to clear the vines from buildings) but you can still carry a "portion" of the Field with you, so to speak.
Making all the Field mechanics stack would be... well, certainly interesting! In the late game it would be a complete chaos and pretty much impossible to balance. But it might make for a fun "alternative mode" :)