Good warning about the W+B. It is extremely easy to get a Seneca II to a forward C of G out of envelope position without pax in the back. I believe it requires an awful lot of pulling on the yoke at just the right time to flare nicely (not that I have ever flown one in such a condition).
I also understand that they fly well with full fuel, full seats, and baggage but that would, of course place them over weight and would invaildate insurance etc.
Mine was a 1999kg certified machine and of course refused to fly the moment an additional weight was placed in it. Clever machines these aircraft that can read certification schedules.