I took some measurements for ya last night, orange.
As i found it (nothing on ssqa, front loader on floor) parked in my garage that has a pretty decently flat concrete floor - 11.25" under the backhoe kingpin. It looked like my rear tires were well on the concrete about 52" forward of there. = ~12 degrees departure angle.
I grabbed a nearly full bucket of moist dirt and measured again, had about 12" under the kingpin now. = 13 degrees.
I measured about 4 to 4.5" clearance between my backhoe seat and the fuel tank cap. Could definitely fix that and have the whole backhoe be about 6-8" closer to the machine. But you know what? That would only improve your departure angle to about 14 degrees. Is it worth it? Probably not.
I forgot to check my rear tire pressure but I think they are at around 25 psi. What are yours at, by the way?
But then I went out and dug some small tree root balls that are in the way of a new project. In practice on my land, I've never gotten stuck from the rear angle. Maybe it drags the dirt here and there, no big deal. Only matters when loading a steep trailer on pavement, I suppose.