I use ultrasound gel. I put it in a restaurant style ketchup bottle and keep it with my strap. It takes 2 seconds. Faster than licking or spitting. I'm a doc so I can get ultrasound gel from my supplier. If you can't find it you can order buh-bump online. Also, if you've been doing this for a while, you know you're not at 180 five minutes into a run. Sweat a little and things will get better. I  can pretty much feel MAF,

I think there is something to that. As I do more lhr running I am more in tune with my body and how I am exerting myself. Can pretty much tell within a few beats what my hr is - once I am really warmed up. Not so much at the beginning of a run because of how my medications kick in. Like this morning it was cold and hr got quickly to 88 while walking, then suddenlyt dropped to 82. Once I get the heart going steadily and having reacted to the meds, its a straight correlation between hr, pace and "feel" - within reason anyway.