Champion rear differential gear oil check

Hello all, new member and two month trike owner. Registered and have been reading posts for over two hours, interesting info, eyes getting tired. I’m not close to any shops so want to do as much maintenance as possible. For checking/changing rear diff fluid maint list says remove seat. All I see is a small loose what appears to be metal plug on right side on top of box/trunk, whatever it’s called, can barely touch it reaching down. I’ve read some online posts about different methods to access, some crazy methods. Shop in AZ bills 3-4 hours labor to change the fluid (2 quarts 80/140 gl-6). This is mind numbing they did not put in an accessible drain/fill plug. I don’t know that I have an issue but like to know the status of everything before traveling long distance. So far I have changed oil/filter, new plugs, flushed coolant, new tires, removed front tire to save $$, sprayed elec cleaner on multiple switches so they function, preparing to tackle air filter replacement. Any help on best method to check diff fluid is appreciated. Tom

I have a champion trike kit also and mine does not have lube in the differential it is packed with grease that you never change your check.