BSPs wouldn't be a bad idea. Or perhaps one of those and a Keystep Pro? That would give you much the same functionality AND also add a proper keyboard controller.
How do you make it portable? Easy-peasy. Go to a sporting goods place that carries more guns and gun supplies than the entirety of Delta Force, and find a suitable gun case. This might sound odd at first, but when you notice that at least one manufacturer of these ALSO makes music cases (ie: SKB), it all gets clearer. Find one that can fit the BSPs...or the BSP + KSP...and then modify the internal foam so that everything fits nice and snugly. In fact, quite a few gun cases have "cubed foam" so that you can modify the interior to your exact liking. Just take your gear measurements with you, do some rooting around, and you should find just the thing you need.
As for FX...you've got a big gap in the tile row. If this is 24 hp or wider, there's your FX module space; Intellijel has a tile that offers stereo reverb, chorus, and delay (https://www.modulargrid.net/e/intellijel-multi-fx-1u)...in short, the basics that are often part of sound design, albeit nothing overly complicated, either to use or in terms of sound. As for anything beyond that, you should do a deep dive on either eBay or Reverb and look at 1980s thru mid-90s rack processors. Back in the day, a Yamaha REV-7 would've set you back a hefty chunk of change...but the two right next to me in the rack only ran me about $350 (yes, together!)because they're "obsolete". They don't SOUND obsolete...they're just not the newer/shiner/faster model of reverb unit, which to me isn't even close to "obsolete".