Bump! This is an old post and I practiced last night so what the hey...I'll respond.
A lot of bluegrass "picking" is gonna be picking "in the rough," beside the stage, behind the stage, and at whoever's RV has the best musicians--which makes a EUB useless. AND, an EUB might be easy to carry, but the amp won't be. You'll need to supply an amp for most bluegrass events. Add to that, most bluegrass musicians will need medication in order to play with an a$$ kicking bass amp behind them. BTDT!
A 3/4 bass will go into a king cab or 4 door pickup. Another option that's cheaper than an EUB and amp is get a cap for your truck. It'll be far cheaper than going electric. Or buy a good used Astro...that's cheaper yet. You'd be surprised where a double bass will fit with a little thought. I could get my 8900 Meisel in a Ford king cab by laying the pax seat forward. That creates a problem if you have passengers. Cap is still good. Just be careful in wet weather. A very large plastic bag will protect the bass from whatever gets into the bed. Used to play at Paramount Carowinds and the bag thing was very useful after they stopped musicians from driving into the park. Always keep some sort of "raincoat" close by for the bass when out jamming.
I'm all for electrifying an upright bass, but if you're going to play bluegrass music, you'll need to find a way to use a 3/4 bass and transport it. A 3/4 upright will fit into a lot of cars that you would never guess...Honda Civic (neck will be over the shifter, but it's driveable), VW Jetta wagon (my present transportation), any van or station wagon. I have an RX300 that the bass fits in with one rear seat upright. This allows 2 pax to ride. Great for local jams. Our Jetta Sportwagon will also accomodate the bass with one rear pax seat upright.
BTW, Cadillac Sky's bass player, "Panda," as often as not, plays a full sized bass. I suppose it depends on whether he's flying to a gig, or driving. He's like Byron House...he'll play anything with bass strings...and do it extremely well. I'm a big fan of electric bluegrass, but typical bluegrass bass players got to have a DB. A lot of venues won't allow electric basses....generally. Bet they don't turn Doyle Lawson away!
JR