Advice wanted on fieldman f73


Hi everyone im new to the site so dont know if iv posted this in the right place, but here goes. Iv just purchased a fieldman f73 on a L plate, its main duty will be to pull my boat about. On the weekends i aint out on the boat i wouldnt mind a bash of off roading in the mountains of south wales where i live. So the question i am asking is what can i do to the suspension to get more clearance and what size tyres should i be looking at fitting bearing in mind i will be using this truk on the road aswell.thanx.