golang: running a main-like in a non-main package

Ok, so we have a package with a fair amount of complex tests. As part of the test suite, they run on builds etc.

 func TestFunc(t *testing.T) {
    //lots of setup stuff and defining success conditions
    result := SystemModel.Run()
 }

Now, for one of these tests, I want to introduce some kind of frontend which will make it possible for me to debug a few things. It's not really a test, but a debug tool. For this, I want to just run the same test but with a Builder pattern:

 func TestFuncWithFrontend(t *testing.T) {
    //lots of setup stuff and defining success conditions
    result := SystemModel.Run().WithHTTPFrontend(":9999")
 }

The test then would only start if I send a signal via HTTP from the frontend. Basically WithHTTPFrontend() just waits with a channel on a HTTP call from the frontend.

This of course would make the automated tests fail, because no such signal will be sent and execution will hang.

I can't just rename the package to main because the package has 15 files and they are used elsewhere in the system.

Likewise I haven't found a way to run a test only on demand while excluding it from the test suite, so that TestFuncWithFrontend would only run from the commandline - I don't care if with go run or go test or whatever.

I've also thought of ExampleTestFunc() but there's so much output produced by the test it's useless, and without defining Output: ..., the Example won't run.

Unfortunately, there's also a lot of initialization code at (private, i.e. lower case) package level that the test needs. So I can't just create a sub-package main, as a lot of that stuff wouldn't be accessible.

It seems I have three choices:

1. Export all this initialization variables and code with upper case, so that I could be using it from a sub-main package

2. Duplicate the whole code.

3. Move the test into a sub-package main and then have a func main() for the test with Frontend and a _test.go for the normal test, which would have to import a few things from the parent package.

I'd rather like to avoid the second option...And the first is better, but isn't great either IMHO. I think I'll go for the third, but...

am I missing some other option?