Hi; From what you are saying there are two issues?
Firstly the design of the seating, secondly the level of comfort. There are a couple of things you could do with the design. You could look a modification that lowers the table to form a base for another cushion. This will increase the area of the seating and allow you to ?snuggle? when watching TV. There are fittings and fixtures available on the interweb, that would enable you to modify the table to do this. You could use the existing fixing points, but would lose the table frame in lieu of a tube type fitting. On some later Bavaria?s this option is actually a powered raise /lower function. Otherwise I am sure with a little imagination and a sketch book you could design something that would work. You may consider a foot stall that could fit in to give that extra leg support? Should be relatively easy to knock up?
The life of the foam is somewhat limited, even without hard use it deteriorates with time. Both the replacement of the foam and /or the covers is something you can do yourself if you have a good sewing machine. (and as Bob says an electric calving knife!) You can get a heavy duty Singer machine that will sew up to 5 layers of canvas for about £260 in Argos.
Otherwise call Jim at JB marine, he is the very best trimmer, upholsterer, I have ever met. He tends to work around the Hamble area. He may have a few ideas on how to resolve your problems.
I have his mobile if you need it.
Best regards
Ant