My new favorite thing.

LPS 2 in the trigger bottle with an 18" straw.

We use to use the spray cans. You can actually control how much you apply with the trigger bottle. Just drill out the end with a #44 drill bit to fit the straw in. You can hold the straw and a small flash light in one hand, aim it where you need it and work the trigger with the other.

https://i.redd.it/oe51yicd2q421.jpg

Edit: I got the straws from Business Aircraft Consumables, here’s a link.

https://www.bac-online.com/default.aspx?page=item%20detail&itemcode=STRAW-16#tab-1