Obviously we are talking about exclusive motor use, because a rubber dinghy will never be able to sail with dignity by rowing or sailing. RIBs are just good motor boats. But for the purchase of a rubber dinghy with a capacity of 400 kg (like the p8) it will also be necessary to calculate the following higher costs (many of which are fixed and independent of the hours of actual use).
Marine engine: choice of a higher power model, proportional to the greater weight of the boat.
Road trolley: purchase, road tax, periodic testing and insurance.
Car: purchase, installation and test tow hook.
Insurance: trolley static risk policy + car liability insurance supplement for tow hitch.
Toll surcharge: traveling with a trailer on ferries (+120%) and motorways (+40%).
Fuel consumption surcharge: traveling with a trailer (+30%).
Maintenance costs surcharge.
Scrapping costs for fiberglass disposal at the end of the life cycle (about €2.50/Kg).
Do the math well and evaluate all budget items carefully before making your choice. And remember: the purchase of a boat includes a statistically very high percentage of regrets.