RAV4 Bj 2015 – off-road suitability, tyres, etc.

Hello, I recently own a RAV4 Bj 2015. Very nice vehicle so far, however two things bother me: – the vehicle is with these 18″ tires for my feeling hard springed (come from BMW..) – I would have liked it to be more suitable for terrain (want to go to Lapland etc.) Accordingly I wanted to upgrade the car… – Underrun protection with protection for gearbox, engine, tank, distribution gearbox I could find so far – I would have liked the car with 16 inch tires on steel rim e, but I think it’s only minimum 17 inch steel rim?! – Air suspension with level control I would like to have.. someone do it by chance? Is there any such thing for the RAV4? I would like to raise the vehicle higher if necessary and hope for more comfort. I have not yet fully recognized the meaning of a heater. We would like to sleep in the vehicle, but as far as I have read in, the heater pulls the battery empty when used for longer periods, so does not bring any advantage here. l. Is that true? Sure.. it spares the engine at cold start, but is a Toyota.. he does it ;-). Thanks for your help!