Its not that impossible to do your own hot tubbing. !
A plastic garbage bin is large enough to hold a roadster tank.
A couple of small cans of drain cleaner (caustic soda, sodium hydroxide)
and some hot water, and you are in business.
BE EXCEEDINGLY CAREFUL IN ADDING THE CAUSTIC TO THE HOT WATER
AND WITH SPLASHING THIS STUFF ABOUT.
The sidecover above is sitting on the hot tub - $4 can of caustic, and some boiling water.
Be exceedingly careful with all of this, that stuff can burn, damage clothes and stuff and damage eyes.
Drain cleaner can be tipped down the drain after - filter out all the paint remnants FIRST.
It does a wonderful job of cleaning out your drains...
Phosphoric acid can (probably) be bought from your local auto store, only takes 250 ml to do several tanks.
Its one of the active ingredients in Coca Cola, although more concentrated as purchased.
Again, makes your drains spotless - makes the garden grow too - very diluted.
Hot caustic will positively eat aluminium, so keep alloy parts well away...
As well as clothes, flesh, eyes and small children and pets.
Keep the lid on the tub at ALL times and well secured when not used.
Note that some modern paints are quite resistant to hot tubbing, and old baked enamel finishes can be pretty tough too, so don't assume this will work for everything...
Make sure too that adding boiling water to your garbage can won't melt it....