>What if there is no inside and outside, no "bubble"?
Solipsism is an untestable proposition, as are all that incorporate the transcendent. It is indistinguishable from fiction. So long as we appear to a) exist independently and b) not share our physical perspective, the closest we can come to Actuality is agreeing on things, which is what we call Reality.
>What if we simply think things into existence (as you seem to propose anyway)?
>This existence would of course only be a conceptual existence and thus more of an "optical" illusion, not "real".
>Wouldn't this leave us with a "thing-less", unlimited, infinite universe - where all "things" are only made up – thought up – via interpreting "undifferentiated stuff", "patterns", naming them, thus creating the illusion of the existence of apparently solid, independently existing things?
We think things into existence but not from nothing, from the mass of Actuality that has no such limitations as ends or boundaries, according to our experiential understanding of how things have worked in the past and how we intend to manipulate them to attain fulfillment of our desires. What ideas our sensory experience corresponds with we call Real in a sense other than the transcendent Actual which can only be accessed over time by improving our instruments and understanding.