I understand you concerns about cutting the crossmemeber. My opinion on the matter is you have to look at the car as a whole and not just localized in that area. You still have the firewall, floor pan and roof structure. The best compensation for removing the center tunnel ware the pictures FABO members posted below.
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One added subframe connectors and structural driveshaft hoop pictured below. And the other shortened the height of the tunnel channel leaving it entact but shorter. I think both Strategies will help control localized flexing of the sheetmetal in the tunnel to keep the spot welds in that area from tearing. I’m going to do both. This is just my opinion and I’m not engineer.