I do agree with Big Pistons - it's a very risky endeavour that needs to be under the eye of a grown-up. Better still, a current grown-up; I once got this wrong and nearly got written off by an arrogant **** with 10,000+ hours monitoring an autopilot, who told me how good he was and listed his extensive formation experience, but neglected to mention that the last time he'd done any was about 30 years previously.
I had a similar introduction to him - 10+ hours with an ex RAF instructor and then another few tens of hours practicing with him. I'd love to say that I have the 160 hours subsequent experience - which I don't. I'm now a few years out of practice and about to start in again, but will be using 10++ hours carefully and iterative workup with somebody I trust before getting at-all close in formation again.
SMAZ - try asking up the road at Thruxton. There are at-least two very experienced ex-military instructors teaching there, and I believe that one of them used to regularly lead formation exercises using their fleet of PA38s. I don't know if they still do or not, but it's worth asking.
G