Excellent idea, but much much sooner than a month before the GOP convention.
It might be best to tie the date to a scheduled CPAC conference to maximize attendence
Yes, details are important. But the result of the convention needs to carry forward an effect up to the time of the national GOP convention.
I think you're onto something here. A couple of points:
One reason the TPM is successful is that is diverse and unorganized/uncentralized, which prevents the GOPe as well as the libs from pulling the alinsky trick of personal destruction.
Secondly, the TPM needs to stay on message of smaller gov, constitutional limits to gov and fiscal sanity. Being a subset of CPAC will help prevent the dillution of their message.
Finally, a convention costs a lot of money, money that could be better spent on elections.