One other option you can try to get temperature info less expensively is by using thermometers. You could try to use a common baking thermometer taped to whatever you want to check, but more industrial-use versions exist that look more conventional and read temp only at the end. That long stalk on the oven units can foul your readings unless insulated.

The other option: do a Google search for "temperature strips". Tempil and others make one-way indicators that change color permanently once a certain temp has been reached. Since you can't know what temp you need to indicate, they also fortunately make strips with an range of temps on them like a thermometer. You could buy a sheet full and stick them onto several places. Start up and run normally, jump out and note strip readings, and then just sit awhile and read again looking for differences in areas affecting fuel.

Your only challenge with this last one is to find a temp range that fits what you want, and finding a source that will sell you just a small quantity. Businesses doing retort food processing tend to use them a lot, and you'll likely need more than just one freebie sample since they are one use only.