citation V & some ultras are now welling for what king air 200's did recently. don't know what kind of flights you will be making, but unless it just totally doesn't fit the profile, there is no reason not to get a jet. both of those models can be operated single pilot with a waiver, which will give the operator some latitude as to how the right seat is occupied. for example, three years ago, i was able to get a guy with your quals named on my insurance for a 560 with a $50 million liability policy because i had the single pilot waiver.
even if you do go with a king air, you are a LONG way from being insurable, especially on policies with high liability limits.
king airs and citations are great airplanes with a long history of fantastic service. there has never been a better time for your buddy to buy one.
good luck figuring out how to make a job out of this.
eta: employer should pay for recurrent/type school, and don't count yourself out yet. as the guy above me posted, perhaps you can get a cfi/mentor pilot to train you in the plane. at the rates that most corporate operators fly, it may take you a few years to get the hours in for insurance, but it may be doable.