Thanks for the input guys. At this point i haven't had much time with the tracks to get a feel for how to integrate extra fills with taste and not sound like i'm sneaking in a bit of bass soloing. A lot have punchy pedal bass lines so there is that solid groove to maintain. ad well. Hmmm......

An added thought:  When I suggested power trios as a guide, I did not mean Z.Z. Top (Dusty Hill was the epitome of the 1-5, part-of-the-drum-kit bassist) or Double Trouble (but there is one track on a posthumous album from before Tommy Shannon replaced Jackie Newhouse, and it's a little closer).
The Who were, instrumentally, a trio, and Entwhistle did it great.  Jack Bruce killed it with Cream.
So did John Paul Jones & Mel Schacher - but I like you, so I won't suggest listening to LZ or Grand Funk......
And outside power trios, try Grateful Dead, Jefferson Airplane, Quicksilver Messenger Service, Allman Brothers Band, and Achilles Wheel for what it sounds like they're talking about in a larger ensemble.

Peter