Is there anyway to puth the Lightroom adjustments on a separate editable layer(e.g., as a smart object layer)?
Not so you can carry the LR changes into Photoshop, but you CAN keep changing the layers in Photoshop AND changing the "same" image in Lightroom - as Mr Schewe says...
So, I think you REALLY want to open the original and keep your layers and LR adjustments.
You do this by keeping the Photoshop edits in your PSD and only ever doing "edit original" on that PSD, and keep your Lightroom changes in a Virtual Copy of the PSD. Changing the "original" PSD in Photoshop makes Lightroom auto-update the view in the VC, and changing the VC in Lightroom changes the image as you would print or export or slideshow etc from Lightroom.
So, for example: (1) you import a RAW into LR and do some initial adjustments; (2) "Edit in Photoshop" which creates a PSD which contains these original LR adjustments, and you add Photoshop layers etc. then save the PSD; (3) back in LR create a Virtual Copy of the PSD; (4) you can then do more Lightroom edits on the VC (which does not change or flatten the PSD as it is only a VC); (5) you can then open the PSD (or the VC for that matter) with the "Edit Original" option and you are back into Photoshop editing the PSD with your layers, so you can make more layer changes in PS and save the file and (6) hey presto the VC automatically updates to show the changes you made in Photoshop AND keeps the Lightroom changes you had made in the VC. Life goes on without losing your Photoshop layer work.
Does this help?
By the way, Mr Schewe, I assume this means it is correct operating procedure to finesse a layered PSD/TIF in PS, then softproof in LR - creating a separate softproof VC for each printer/paper you want - THEN you can go back to the layered PSD/TIF in PS to perform more finessments, and all the softproof VC's update with the PS changes and are still (depending on the PS edits you did!) A-OK and ready to print.