Paul, if you're willing to give up 50% of the profits, there are surely several ways to achieve something like what you are seeking.
The suggestion of an aggressive hedge fund seems a valid one. Rather than trying out individual candidates to trade your money (and possibly lose it), you could research which hedge funds have the best record, and choose the best candidate among them, based on their established record, rather than trying out individual traders to do the same job for you. The hedge funds probably will give you better than 50% of profits, and it won't be dependent merely on personal trust.
When you consider how much a 50% cut of profits could add up to, if things do go successfully, and figure how much it might cost you to sign up with even some of the pricier trading tips services, you might be able to find at least one such service that (for a price, which you seem willing to pay) would issue trading suggestions that you could then implement in your own account, without having to worry about sharing access to your own account with anyone.