Hi Roger,
I think both are valuable options. You could have your field marketers work in simple campaigns or your could create multi-step campaign templates. Reporting and settings should be identical in both scenarios. I am not 100% sure if you mean the campaign fields like "Product", "Region", "Campaign Type" when you mention "hidden campaign fields", but if yes, you can also configure those in the campaign settings for the simple campaigns:
The simple campaigns are visible in Insight exactly as multi-step campaigns, to my knowledge. Templates emails and segments for the field would certainly make their life easier. Contact level security and asset permissions would make your setup almost completely bullet proof then.
Best regards,
Matthias