Free Roaming
 

Does SH5 allow a start from the pen and allow sailing the seas without having to fulfill or follow a predefined campaign or task?

Stock game (v.1.2.0): NO, you cannot free-roam through the campaign because you have to succeed against the 'Progress bar' where you must sink a nr. of ships in order to proceed to the next campaign chapter. At the beginning you start a tutorial where you don't start from the pen but in open sea, else you always start from the pen.
Athough you are free to go where you want to sink ships, it's all about your tonnage IN YOUR MISSION AREA for advancing in the campaign, this is a limitation of the stock game. Your tonnage outside will not count, although it will count for promotions etc.

TWoS mod: YES, you can free-roam through the campaign because all objectives and missions are purely date-controlled (the Progress Bar has been wiped out). Your successes in sinking will reward you with promotions and crew points faster, but only the DATE will determine your campaign chapters, so you can play it all the way you want, take missions or not, it doesn't matter, go where you want to sink ships, but your mission area will yield more contacts.
You always start from the pen. The tutorial and other video sequences are skipped.

However, In the stock game or with mods you can always use a 'cheat trick': You can start from a special campaign chapter by typing 'silentotto' in the campaign chapter screen, so this will allow you to start from where you want.
Plus, you can also change your date with KSD Commander or by editing your savegames. I have made a guide for this, it's not sticky yet so search for 'guide' in the search tab in the SH5 mod section.

Thank you.