Hey Nils,
I'm in a similar boat, freelance design work alongside a small rental property gig. I also used BolderInvoice.com for a while, but ran into the same limitation. I recently switched to Zoho Invoice, which is free and supports recurring invoicing with solid customization options.
Another one worth checking out is Invoice Ninja, it's open-source with a decent free plan and good automation features. Both integrate well with payment gateways if that’s something you need.
Hope that helps! Let me know if you want a quick comparison.
I was in a similar place managing invoices for my small business. I also needed regular invoicing, and I found that customized solutions could really help. I came across a company
https://ddi-dev.com/ that develops specialized software, specifically invoicing systems. They specialize in this and it's great for creating flexible tools. If your current software lacks features, it might be worth trying a custom solution.
Gregory