This extrusion could likely be done on a good-sized radial arm saw as well, but rigidity would be key, and those require gobs of unavailable room as well. Bottom line is I need to work within my currently available equipment set.
Ouch...
As someone who has processed a tad over #200K of 4.5 x 7 U-channels 3 years ago using a 24" table saw with a 14" custom blade, my suggestion
would be to find a way to overcome your space limitation.
If you can, then a table saw can be the cat's meow on the very cheap.
For rigidity, you can install a stabilizer bar on the front of the arm, but that will limit you to 90deg cuts ( or wherever you install the bar )
You also want to stiffen up the slide so it does not "bounce". I've used UHMW shoes pressed against the round guides and it worked pretty well.
The blade likes to "climb" into the material, so instead of pulling, push the blade into it so the saw is cutting upwards.
For lubrication WD40 is barely OK and very soon you will find it quite miserable to use and breathe in. There are specific MQL lubrications
out there for AL that require very little amounts to be squirted on the blade or the material. You can also use something like Evap-lube
or other vanishing lubrications.
The most important part however is the blade itself. Pretty sure you know this, but saying it anyway: Do not go to Home Depot or similar places
to look for a suitable blade! Get one that is specific to cutting Aluminum! There are many places that have off the shelf, or can make one in a jiffy.
My 14" blade was made complete in 5 days ( though they've had the blanks ) and it was flawless for thousands of cuts!
If you need one, Specialty Saws in Simsbury CT is one source.