[EDIT: I have updated this post to provide solution for the campaign transfer problem, and make a note about TDW Generic Patcher]
There is another solution for the Steam version to return the game to a moddable v.1.2.0 status, and remove all modding limits - and let the Steam interface go down the river, you won't need it anymore.
You must have your game updated to 1.2.0, Steam users have this one, or the patch is still on the net but you need to use the right one for your game type (Collectors Edition, or else). After updating, install TWoS and backup all these files:
EnvSim.act
kernel.dll
sh5.exe
SHCollisions.act
SHSound.act
SimData.dll
After that, you can uninstall TWoS and the game, re-install the game and overwrite your game files with the above ones. (Steam or U-Play owners do re-install 1.2.0 and overwrite the files above, old installs of 1.2.0 simply overwrite the files above).
You will then have a playable SH5 version 1.2.0 updated with TDW Generic Patcher and from there you can play stock or install any mods you like. Halejuja... And kiss good bye Steam or U-Play interfaces
Download and keep the very important mod 'TDW_GenericPatcher_v_1_0_168_0', put it in your game and apply it even after replacing the files here above, so you can be SURE to have a correct game setup upon which you can install mods you find here in Subsim.
After this you want to copy the entire SH5 game folder to a portable hard disk to be re-installed in the future with a simple copy-paste.
The drawback is: The campaign transfers will not work if you use different mods than TWoS. If you use your own modlist, then it must at least contain the following:
---------------
Your modlist:
---------------
...
...
TDW NewUIs 7_5_0
...
...
Open Horizons II v.2.5
OHII v2.5 - No Stupid Tonnage Bar_Free Style Campaign v0.1_NewUIs v7.5.0
...
...
---------------
If your modlist contains the 3 above - in that exact order please! - then you'll be able to transfer campaigns correctly in all cases.
Is all this procedure legal?
Yes, because based on game mods exclusively and you already own the game
But why should Steam users do this? I have mentioned all this to cut the story that Steam versions are limited - they are not after all this dance. But else, I see no better alternative to TWoS, maybe some other Megamod like Sober did, but else there is nothing worth to mod and spend your time with it (if you simply want to play SH5 and enjoy), you'd need to be an expert of SH5 to make the stock game play acceptably, I know what I'm talking about because I have 2 SH5 versions on my rig, and my stocked modded one is far from reaching the quality of TWoS.
XS