Being a bass player and a 5 string banjo player I might be able to lend some input. Finger picks come in various thicknesses, like guitar picks. You'd want some fairly stiff picks for bass otherwise they will bend into your fingertips when you play. The finger picks I use are called "Showcase 41's". They're not super thick but they don't bend while playing the banjo. However, banjo strings and picking technique are a lot different from bass so look for some thick picks like the Sammy Shelor stainless steel finger picks. Those won't bend...they're the stiffest finger picks I've ever come across. They're pricy though...$25-30 for two, compared to $7 for a couple of Showcase 41's. Either way you go, you can get them from Janet Davis Music Co in Arkansas, via the website or probably get a pair at your local guitar shop. A good set of finger picks will last for years...I still have a pair of old Nationals that I bought back in the early 70's. I'd recommend you get a pair of 41's and see how they work for you...you can always spend more on the Shelor stainless picks if it's something you want to go further with.
Also: Thumb picks are very usable on bass - between bass and banjo I go through about a half dozen thumb picks a year- the tips wear down and they eventually break at the thumb loop if you use them a lot. Match your thumb pick size to your glove size -if you wear size L gloves, get size L thumb picks. And you can drop them in boiling water for a few seconds and shape them to your thumb for a better fit. Metal finger picks are size adjustable so one size fits all.
I was in a band for several years as banjo/bass player...we lost our bass player to illness so we started rotating bass among the 3 front line players. When I'd switch from banjo to bass I tried leaving the picks on and it didn't work so well for me. To get a good thump on the string you have to bear down on the picks, which will change your playing style completely. I normally play bass with finger tips but on a couple of tunes we play I need a pick for certain sections, so I keep a thumb pick wedged into a fold of my strap. If you're a pick player, thumb picks work well for bass...they're thick and it's pretty hard to drop them while playing.