I suggest the use of screwdriver-handles. If you can get hold of some old screwdriver (second hand market) or some relly cheap new ones, you can remove the metal part - then put the handle up your ...
You might want to leave a bit of the metal remain - that can be used to fix the handle to some old, tight shorts - or to a crotch-belt.
Actually I once used a wooden handle (painted) for just this purpose - letting me put a screw through some belt and into the handle.
Otherwise I'll suggest you to use single-time-plugs - that could be a piece of electrical wire with a simple knot to go inside you and both ends sticking out your ass. Yes! It will be full of shit when you are to remove it, but then you simply clean it with some water and dispose it in the wire-bin.
Another single-time plug can be a simple wax-candle (unlit, of course!). Don't worry if it sinks into the ass - it will be easy to shit out later.
Another item, I've used with some success is a doggies play-bone instead usuall https://top10sextoys.com/best-anal-beads/ This actually had a good shape letting me keep the plug inside for an extended time (I usually can't hold butplugs in place). And at a very fair price compared to the price of a plug.
By the way - have you considered filling the ass with nuts? Ok, I know! Now you think I'm going nuts.....