right - absolutely NO brim on that octopus - It will weld all the links together.
And yes - rafts on a longish print will pretty much always weld themselves to the print.
Just plain avoid rafts.

and it is actually a bit of a sod to print.
The tiny little links between the sections are really narrow and lift fairly easily.

Like everything else, the sapphire laughed at such things and I knocked out a re-mix of it with the same legs but a spiders body :-)

Okay - so we need some print setings.

what is your extrusion ratio ?
speed of first layer
z axis offset
bed temp
print temp
print speed.
Retraction settings

And what is your objection to decent print glue ?
Great stuff.
Unless you have PEI or printbite (and often even then) a decent print glue that sticks when hot and releases when cold - is the answer to a lot of problems.
To be fair PEI also does that quite well.

Me I'd order a sheet of self adhesive PEI. It's about 0.2mm thick - get the cheap stuff, so has no effect on bedtemp and all calibrations can be dealt with simply by adding +0.2 to the z-axis offset.
It should be around $15 for your bed size.

The last sheet I bought was £7 and that was 250x250 and trimmed it to size.
So yours shouldn't be that much more

In the meantime try some PVA gluestick from a buckstore.
heat the bed to 60c.
And run the gluestick over it lightly - you don't need to press down.
do it a couple of times - leaving about 5 minutes between layers. It forms a thin plastic layer.
Pla love it.
I've never bothered trying to print on glass and none of my printers have use their original print surface.
'cos basically until manufacturers start using PEI - I'll keep sticking PEI on top of whatever crap the printer come with :-)