How about don't increase the insurance costs in % but increase the module value. Instead of 5000 credits your MC would cost 15000. This would also increase rebuy costs...
I'd take that one out of all the ideas so far; makes sense that insurance needs more funds to cover replicating some crazy hotrod over a more simply tuned or shelf-standard vessel; they probably have to pay some reverse-engineering team to do the work. I bet they have a holofeed of the team showing their daily lives. You know you're watching it on those long runs to Hutton.
ROADTRIP: REVERSIX MEETS FARSEER FOR THE DOPE ON FSD TRANSCONDUCERS (Plus: Chuckie gets drunk in 0G- again!)