Through the floor with no fall, or through the wall with fall-A septic question

Good evening all,
I'm wrapping up putting in my own septic. I've run into an error in measurements & would like advice on how best to proceed.

The fall between the home & the septic is the issue. The current pipe comes down off the main line, then drops through 3in ABS about 3ft (the crawl space below) into a 90. The distance is 33 ft. The fall averages to be at a 1.5 grade through the first 10 ft, .7 through the next 10 ft, and .3 through the last 10 ft. Water flows from point A to point be. "Solids" have not been tested yet.

The only option I'm aware of give a greater fall involves moving the 90 to above the slab & through the side of the home. It's a manufactured home, and the skirting can be punched through. Doing this would gain anywhere from 1ft to 4ft (and thereby the necessary 2% grade). HOWEVER...the pipe would be exposed to the elements. My thought would be to put a cinder block wall around the exposed area & fill in dirt around the pipe vertically and horizontally. Or, would insulation be enough?

I suppose a 3rd option is to have the septic company come & pull it up while I excavate below. That's likely the most expensive choice.

Any feedback would be appreciated.
JT

my code says 1/4" per foot if you pitch it too much
you will leave the solids behind

I think the weather would still affect it check and see if you can
heat trace abs/ PVC I piped a shower valve in a garage we all
the garage had no heat but It was in an insulated wall
It's still there and working fine