I taped a stuffed sock to the end of a painters extension pole and saturated it with the lubricant. I can then reach under the slide topper to get the top seal on the slide out. It works pretty good. I lubricate the inner seal the way that you describe it by bringing the slide in about a foot, so far no harm.
2022 RAM 3500 DRW, 4X4, 4.10, 6.4 Hemi, 50 Gal Gas, Curt A20 hitch, Tire Minder
Traded: 2018 RAM 3500 DRW, 4X4, 4.10, 6.4 Hemi, Curt A20 hitch, Tire Minder
2018 North Point 315rlts with most of the options.
Dish Hopper With 2 Joeys & Birdog Meter, 2-2K Champion Generators