In Autair we operated several Vikings for many years and YES they were most definitelty nose heavy.
Our procedure was that we ALWAYS carried 300 kg of ballast in the rear hold on empty aircraft.
On turnarounds, ballst was loaded as bags came off and ballast came off as bags went on..
Plus the Viking had air bag brakes which could be a little "pro active " and landing was a battle between stopping before the end and tipping up !!
We sold one of the Vikings to a company in Southend who had not operated Vikings before. The crew arrived to take the aircraft home and we ask the crew to sign for the 300kg ballast so that if we didn't get it back they would pay for it. The crew decided there was no point in going to all this hassle so told us to take the ballast off and be done with it - which we did.
1 hour later we were asked to get some engineers over to Southend to get the aircraft tail back on the ground !
The aircraft would stay with the tail up after its performance and trick was that to not let it drop back down as it generally drove the tail wheel up into the fuselage !
