Advice on rear springs please.

Hi all.
I've driven to Bulgaria and back twice now in my 300TDI ( 1966 ex N reg )
What with my home made roof rack and the back fully loaded, it wasn't surprising I was getting flashed at all the time, due to the headlights obviously beaming way up at the wrong angle, and blinding passing aircraft pilots. I also had to be careful going over bumps as I could feel the car "bottom" on the stops on many occasions.
So my question is, can I just fit stiffer springs to stop both the bottoming, and at the same time keep the angle of the lights as near to normal as poss, ready for my next long trip back in the spring.
I fitted some bog standard Britpart shockers on the rear around a year and a half ago. Lift is standard height, and I don't really want to put some more shockers on if I can get away with just the springs. So as I said, can anybody recommend / advise on the best solution please.
Thanks in advance.
Dave

Bearmach heavy duty springs in blue

disco2shaun said:

Bearmach heavy duty springs in blue

Click to expand...

They'll do the job, but how often is the Disco fully loaded? Reason I'm asking is that they can make for a harsh ride when car is unladen. They also do these which handle weight well but give a softer ride.