Would an aircraft portable PTT (push-to-talk) switch make a good a-p engagement switch for something like a combine where it could be velcroed to the hydro stick? I'm thinking of the venerable Telex unit. The usual 1/4" phone jacks would not be utilized, but the button would simply become a "momentary-on, momentary-off" switch...right?

They've been around for years & are fairly comfortable & fairly resistant to abuse. They'll usually wrap tight if the velcroe backing (foam) hasn't dry-rotted from sitting in the sun forever. I'm assuming they could be found on ebay somehow.

http://www.protravelgear.com/store/guide/shop_by_brand/telex/telex_ptt_300_push_to_talk_switch.cfm