I wouldn't suggest that you sell off the current 1 x 84 skiff. You WILL want it for adding more modules later on. If you doubt this, contact me in a year's time and tell me about what you repurposed it for.

But instead of trying to build an entire synth in a 1 x 84 skiff (always a bad idea...you WILL wind up compromising subsystems in this build if you do!), I would suggest that you check out a Tiptop Mantis. We say that loads on here...and it's not JUST because of the 208 hp of space you get, but because the Mantis is a sensible size, has really good power specs, is lightweight and portable enough that Tiptop sells a custom gig bag for it, AND you can stack a second one with its special stacking brackets to double your space.

As for the skiff...one really good idea might be to repurpose it as a controller/sequencer cab. You could put a Tempi/Rene mkii pair in there for sequencing and touchplate control, then maybe jam your performance mixing in the other half-ish, maybe with space to add a couple of CV faders for "remote" control of other modules. That would get two types of potentially chunky modules OUT of the Mantis...which, in the end, gets you still MORE space in that new cab. People don't seem to think a lot about the case implementations, and in the end that should actually be one of the FIRST considerations because that's one that depends on both you AND your available studio space. And you'll also hear it said that you should always make your case(s) too large...because, eventually they won't be!