There's no way I'd risk checking gearbox oil with the engine running. There's a chance you could be there days with your arm stuck between the engine and bulk head. Well, if you've got manly arms:lol:lol
I use an Elty set up ish. I use the flexi nozzle from a 1ltr oil bottle to extend the dipstick tube and a piece of flexi pipe with a small funnel in the top.
Bit of a ballache but it works.
Check the level when it's warm. :thumbs
We've friends live in Carluke. Met them 25 years ago in Tenerife and we try and visit every other year, they do the same. Scotland is a beautiful place and we have had the privilege of our very own Scottish tour guide :D:thumbs