Kia Ceed spring strengtheners

Laur2213

I have a Kia Ceed and love it for towning. It's my second one. I always keep within weight and nosewaight limits. However I thnk the car goes down too far at the back. Both cars have done this even iwth some shopping or a few people in the back let alone
a caravan. When loaded up for a trip to France it looks overloaded though I'm certain it's not and it also make the hitch quite low so it can catch on ramps or when boardng the ferry etc. I'm thinking about getting spring strengtheners fitted. I  believe they
are wee rubber things things that fir inside the coil. Anyone tried this? What would you recommend for a Kia Ceed? Thanks.