Hi Tiny,
I'm glad you're for real and I wish you well. Back in the old days, 2006, when construction was a paying trade, I did that for a living too.
I don't know how long the potato will hold a smokey flavor after smoking if you smoke it first, for say an hour at 180*, then hold it until you're ready to finish it off in the oven. I suspect that it will hold the flavor pretty well though.
Careful about the saran wrap though, since it would be essentially the same as foil wrap and could lead to very serious food safety issues.
How many potatoes do you need to bake, and how many will you sell(at most) in a 30 minute period?
I ask because restaurants that use baked potatoes usually have a rotation baking schedule where they add a small tray of potatoes to the oven every 15 minutes as they remove a small tray that has been baking for an hour. A digital timer that sounds every 15 minutes makes this a very easy process. If you're selling most of these potatoes at lunch, you could just throw in a couple of trays at 9:30 to have them all ready by 10:30, but if you need them throughout the day, the rotation system can give you top quality, freshly baked potatoes every few minutes.
All this is based on the assumption you have room for a small oven in the trailer and access to power. Maybe not a good assumption. But being a fan of stuffed potatoes myself, I can tell you that a well made potato is something people will come back for, so I'd do it right or find something else to top with meat.
Here is a small oven that would work well. It says it will hold 4
half pans, but with potatoes being thicker, I suspect that it would hold just two. Anyway, you'd get 4
quarter pans, that would each hold about 6-8 potatoes, then starting in the upper left corner of the oven, you'd add one pan, then 15 minutes later add another upper right, then 15 minutes later lower right, then lastly lower left. On the hour you'd remove the upper left and add another tray of raw potatoes, and so on and so on...... Using a 40 count potato, you could generate 24-32 potatoes per hour and they'd all be fresh and tasty.
Small Oven Depending on your needs, a home style counter top "toaster oven" might work fine, but I don't think you'd have much success with the microwave. They don't do one potato very well, and if you're trying to do multiples you'll find they take as much time or more than a regular oven.
Go to the pro section and do a search for "prison chef". You'll find a bunch of posts from several years back discussing various menu items to sell from his mobile kitchen. Might get a few ideas.