It's going to be quite hard. Catalan identity, as in distinct from the overall Occitano-Romance group (linguistically speaking) doesn't appear before the late XIIIth/ XIVth centuries. At this point, Leonese-Castillan political (and cultural) hegemon on the peninsula is already established.
We could try to have a deeper Occitano-Romance presence and area in the Iberian peninsula : deeper Frankish presence during the IX/Xth centuries.
It wouldn't be, though, a Catalan identity but an enlarged Lengadocian one with a different genesis.
As for something more than, say, the 1/3 of the peninsula, that's simply not possible. The catalan specificity (either as part of the Old Occitan continuum or as a Occitano-Romance ansbau language) was built on the distinctivness with the Hispano-Romance ensemble that dominated the peninsula right since romance speeches emerged in the Late Antiquity.
You probably could have a kingdom emerging in Gaul (Septimania), Tarraconensis, modern Levante that would take control of the whole peninsula, but it would be totally submerged linguistically speaking.
But Aragonese is, iirc, rather closer to Castillian than it is to Catalan. Why would they preferentially expand that part of their population that doesnt speak the national language?
Well, because you don't have such thing as a nation-state linguistical policy in Middle Ages (mostly because you have neither the institution or mentality for), and if one language was prestigious enough to be used "internationally" then, it was more Old Occitan than pyrenean speeches.
If Aragonese was already that distinct than Castillan speeches (and that's quite something already to assume), it's not as Aquitain and Lengadocian settlers weren't present either trough commercial and pilgrimage way (as in Jaca) or in the conquered regions historically speaking (at the point that the language of the population in southern Aragon in the XVI was still said being "lemosin")