Personally, I think Lightroom Classic CC would have been a better choice. You could have gone through and culled Your images and then created a collection of those that you wanted to work on and shared that collection. That shared collection would have been available to you on your mobile device to work on while traveling. Adjustments made while traveling would be applied to the master images. But that's your choice. Working in that manner, shared collections don't count against cloud storage.
Selectively adding files is trivial. In the plus sign dialog (Lightroom CC's import dialog). Select the folder you want to import from (or the card/device) and hit "review." In there simply select only the images you want in Lightroom CC (the little checkmarks).
Deleting stuff you no longer need is done by selecting the images you don't want in there anymore and from the edit menu selecting "delete photo (s)"
Personally I think the best of both worlds workflow is to mainly use Classic and sync smart previews from there which show up on my iPad and other machines. On the road I normally take a small laptop and import images on there in Lightroom Classic in a small travel catalog so I have full editing and keywording features I expect. When I get back to the office I simply import that catalog into my main catalog. The other workflow I've played with but that I don't like much because of the extremely limited feature set of Lightroom CC is to take an iPad or use Lightroom CC on the small laptop which will sync over the cloud back to my Classic catalog. The syncing is nice but I am usually in places with terrible internet so not very useful. I wrote about this workflow back in 2016 and even though Lightroom mobile has been renamed to Lightroom CC and has been improved quite a bit and there is now a desktop version, the same problems still stand: Jao's photo blog: A mobile workflow with Lightroom?