Most shops won't install one because you have to remember to leave the truck out of gear. They have to override the neutral safey switch and if it is left in gear, it is likely the vehicle will end up somewhere you don't want it, not only damaging the vehicle but whatever the vehicle runs into while the starter is cranking.
Those that will, require you sign a waiver absolving them of all liability in case you do forget to leave it out of gear. With the lawsuit happy society we live in now, I imagine finding a place willing to go the waiver route is going to be a difficult find.
And, I imagine due to the same liability concerns, not to mention a lack of market, makers of remote start systems for manual transmission equipped vehicles are few and far between.
You may have some success in the international market, where manual transmission vehicles are more popular. European countries would probably be the best place to look.
Alternatively, if you are looking for something to speed up the warming of the vehicle on cold winter days, you could go the route I did and install an engine block heater and oil pan heater like I did. The vehicle won't be warm when you go outnto scrape the ice, frost, and snow but it will warm up a lot faster once the vehicle is started. You just need to remember to plug and unplug the cords.
To mitigate the ice,frost, and snow, you can garage it or put up a car port or get a cover for the windshield if putting up a car port or putting the truck in a garage isn't an option.