Help ! ! !

It's getting a little chilly here in Toronto, Canada, about 40f, and my 1990 F250 Diesel 7.3 NA is getting harder and harder to start.

A bunch of reasons:
I drive it about once a week. I wanted to drive it a little more, but every time I have to plug in the battery charger after 30 minutes of starting attampt.

The batteries are a little weak.

Two glow plugs are out, I want to get some good constant duty ones, but they are about $35 a pop, too expensive. The GPs are on a manual switch.
One injector return cap is leaking a little. Since I have a electric pump, that's not be a big deal.

(I run a single filter, two tank WVO system, most of the time I have to start on some kind of veggie oil and diesel mix, cold. )

I thought about install a diesel fired coolant heater, but they run $1500 to $2500, not my taste.

I heard it somewhere that you can easily start a cold diesel by inject ether into the air intake. I'm thinking if propane can do the same.

Can I get a small 16oz camping stove propane, connect it to a hose, stick the hose into the cap of air intake housing. Everytime I start cold, I just screw on the hose, let the propane fill the air intake, and then start. Is it going to "boom", started, or "boom", head fly over the hood?

Can anyone help me here?

Norm