I too am sure that you could position two jackstands under it 60 seconds after I pulled it into your shop.
But the issue here is: ..... that you absolutely could NOT have the loader disconnected, and resting on those jackstands in 60 seconds!
The L48 loader is NOT a quick disconnect loader!
I’m thinking that’s why there are a variety of solutions to the problem utilized by different operators.
Some, such as me, have loaders that are practical to simply remove. We remove and reinstall often enough the process becomes very quick and easy. Removal is a viable option for those type loaders in addition to the options for loaders which are not practical to remove.
Some loaders, such as yours, are not practical to remove. Some operators of quick attach loader machines never remove the loader or don’t have an acceptable place to remove it so remove/reinstall is prohibitively daunting for them. For those loaders and situations, removal is not a viable option. The options mentioned in this thread other than removal; tall jacks, chaining to an adequate overhead structure, or hydraulic cylinder sleeve type blocks would be more appropriate for working under a loader such as yours.
Regardless whether your loader is practical to remove or not, if lifted to gain access for service, it must be mechanically supported to create a safe working environment due to severity of bodily injury in the unlikely, but occasional, event of a catastrophic hydraulic failure. To me, it’s no different than working under a vehicle without jack stands, blocks, or some other redundant mechanical support device.
That said, I fully admit that is my opinion based on my experience with sudden catastrophic failure of hydraulic devices supporting loads over my person which would have severely injured or killed me but for adequate mechanical redundant devices. I am not your father or wife or boss so if you choose to work under your loader supported solely by the machine’s hydraulics because the loader is impractical to remove (or any other reason) and you don’t wish to employ any other alternatives to secure it, I certainly wish you well and hope your loader never crushes you.