Get just about any micro amp, add a tube or tube sounding compressor (EBS MultiComp is what I use), and a Tech21 BDDI or VT Bass or any other modeling DI (heck my Zoom B2.1u has some great amp/cab sims too). Voila, lightweight and versatile rig.
I second this motion. My rack mount tech 21 Vt bass with Aguilar 750 and 410 sitting side by side with my SVT 810 sounds identical. Seriously you won't be able to tell the two apart.