Shower Pan to Waste Pipe dilemna

[pipeLAID]

I have a Manufactured Home. Yanked out a rotten broken old tub and am replacing with a Lyons Shower Pan and Wall Wrap. The pan requires a 3" Drain, and my homes waste pipe is 2" ABS.
Heres my Issue, i can't access the pipes from under the house, or from the sides, its a Back Center Drain and I'm at a loss for how we should build up the plumbing to get it all to not only fit, but while not being able to grab the pipe and use our hands to guide the pan and drain into place.
YouTube has been worthless unless I've missed something.
Any suggestions from the professionals would be welcome. I've attached a photo of how the alcove sits now with a old drain still attached, and a Install Instructions from Lyon for the Shower Pan.

 

[Twowaxhack]

You’ll need to access the piping and find 3” pipe underneath or run a new pipe around the house to the septic tank, and it must be vented.

It’s that simple to explain, maybe not easy to do. That’s how the cookie crumbles.

 

[breplum]

3" drain, not likely. Probably what you are looking at is the hole, but any normal shower drain fittings are two inch.

 

[havasu]

I believe most drain assemblies are 3' in diameter, which allow a 2" pipe to slide over it and seal.

 

[pipeLAID]

When in doubt measure out haha. The people at Lyons told me its imperative i use a 3" down pipe from the Drain to stab the pipe