I would say my blog on package structure still holds true https://dev.to/kevinjump/early-adoptors-guide-to-umbraco-v14-package-structure-3i67 and if you want to multi-target in anyway, my recommendation would be to have two projects one for the RCL assets in v13 and one for the assets in v14, a core library with your buisiness logic in it that can (maybe be shared) and package that builds for each version. i haven't tried this (yet) but its what i would do. you can see how we split this in uSync (its not multi-targeted, there is to much core stuff changed for us to do that with uSync). v13 - has an 'assets' project for the front end : https://github.com/KevinJump/uSync/tree/v14/dev/uSync.Backoffice.Assets v14 - has a

uSync.Backoffice.Management.Client

project doing the same thing but for v14 front end... https://github.com/KevinJump/uSync/tree/v14/dev/uSync.Backoffice.Management.Client both those projects are the rcl elements of uSync.