I come from a 20+ year MSAccess mindset, and I can tell you that QuickBase tables don't seem to care about numbers of fields, so I embrace that fully because QB makes it so easy to do it that way. I have one table that's the hub of our application (Clients) that has about 1000 fields. I have other tables with hundreds of fields. I don't see any performance issues with this.
The only thing you have to watch out for is the 500 MB single table maximum database size, but lots of fields usually don't blow that - it's lots of records with a field or two that is multi-line text and has lots of text in it. Our Internet Webform Response Leads table qualifies for that, and I'm constantly having to beat it back using Data Collaborative's excellent inflate/deflate utility which archives multi-line text field text into a linked file attachment. But I never worry about adding more fields to an existing table if that's the right approach to represent our business logic using proper computer science normalization rules. What gets me to 1000 fields in my client table is the gazillions of summary fields from dozens of other tables that are related to the client table.
Don't make it harder than it has to be. Add those new fields in the existing table. Use tabbed/buttoned sections in the single form, and just make sure your field names are somewhat consistent and organized so you don't drive yourself crazy.