Mike,
Biggest concerns are ventilation and heat. I would check the back of the instruction manual for minimum clearances to combustibles. That will define the basic shape of your enclosure. The next issue to consider is how you are going to refuel and check the oil on your unit while it is running. You want to make sure you can gain access without too much trouble, especially if the weather isn't too nice. Maybe a lift up lid that you can shackle down so the wind can't catch hold of it?
For your first iteration, I would go for very simple construction, grab a 4x4 and a sheet of Ply or OSB. Put a 4x4 post inside each corner, and screw your sides onto them, but don't go all the way down to the bottom, Leave a couple of inches for air to enter the engine. On the 2 ends, don't go all the way to the top, leave an inch for heat to escape. Using 4 x 4's also gives you room to add your rock wool on the inside. (try to mount wool on the bottom of the lid as well) Have the top hinge with strap hinges and latch with a hasp. Slap a coat of paint on it to give it a little protection from the weather.
After you figure out everything that is a nuisance during this storm, you can redesign when you have the time.
Just be safe, don't have it too close to the house. Keep the spare gas in a separate location.
Biggest concerns are ventilation and heat. I would check the back of the instruction manual for minimum clearances to combustibles. That will define the basic shape of your enclosure. The next issue to consider is how you are going to refuel and check the oil on your unit while it is running. You want to make sure you can gain access without too much trouble, especially if the weather isn't too nice. Maybe a lift up lid that you can shackle down so the wind can't catch hold of it?
For your first iteration, I would go for very simple construction, grab a 4x4 and a sheet of Ply or OSB. Put a 4x4 post inside each corner, and screw your sides onto them, but don't go all the way down to the bottom, Leave a couple of inches for air to enter the engine. On the 2 ends, don't go all the way to the top, leave an inch for heat to escape. Using 4 x 4's also gives you room to add your rock wool on the inside. (try to mount wool on the bottom of the lid as well) Have the top hinge with strap hinges and latch with a hasp. Slap a coat of paint on it to give it a little protection from the weather.
After you figure out everything that is a nuisance during this storm, you can redesign when you have the time.
Just be safe, don't have it too close to the house. Keep the spare gas in a separate location.