I would say lease back would be the way to go. I just went in partners with a guy that owns a 141 flightschool and 3 FBOS, I am now a recent new owner and operator of a 135 cert that I obtained from scratch. If you are only one guy doing it, I would say it will be very hard!! It is not impossible and it doesn't require as much money as people think, but it is still very time consuming and that is all you can really devote yourself to as I have done. WE have a leaseback Duchess at our school and it seems to work pretty good for the owner, but it is not a good charter plane, due to the reasons Timebuilder gave. In fact, he is dead on, you are not going to find a twin that is good for training and renting, that will be good for charter, it will almost always be to slow, carry to little, and not be comfortable enough for paxs.
I would say unless you have dreamed of owning and running your own 135 for years and years, then don't try it. You kinda have to love it to do it, cause the money can be good, but it is hard work and you have to set things up just right to make good money. I have always wanted to open one and run a 135, so for me, money almost aside, it is a dream come true, so moeny or not I am really happy and loving every min of it.
I would say we would be interested in your twin for lease back at a new location of one of our 141 schools, but I am sure I am to far away for you to enjoy using the plane.

) Most of our new 172's are all lease back aircraft and our owners are very happy with the situation.
Good luck, and if you need some more advice let me know, but I have to say you have had some really good people above give you a lot of great advice. Take care.
Oh btw, as far as buying a 135, be very careful as to the history of that 135, but like I said I wouldn't even go that route in your situation.
SD