I realise you prefer low wing but that knocks several aircraft that could meet your requirements out of contention. Namely Cessna's C172 RG, 177 RG and C182 fixed & RG. Advantages for high wing include giving people more opportunity to view the countryside passing by, lets you load in the rain without getting too wet and has doors on either side for loading without having to clamber onto a wing.
The C182 series are a rather good 4 seater with range and baggage capacity but with the downside of 6 cylinders to pay for compared to 4 cylinders on the others.
172RG will manage about 135-140kts @ ~40lph
177RG about the same with more leg room but I find a bit less headroom @ ~40 lph
182 about 130-135 kts with great of payload/range ability @ 45=50 lph
182RG about 150kts and similar payload/range ability @ 45-50 lph
No matter what you get I strongly recommend you have an all cylinder engine data monitor & fuel flow installed if it's not already fitted. Pity Europe doesn't have satellite weather available 'cos that's about even on the 'recommend' list.