Wax boil/VPI that solenoid
Suppose you have a V volt solenoid with N coil windings laid out in L layers.
In solenoid windings, you only have very low voltage between adjacent windings - just V/N. Thus, a simple varnish will suffice for wires in one layer.
Between each layer, you have 2*V/L voltage, and you can use wax-impregnated cloth between the layers, or mylar salvaged from the rebuild - this being more important on the end of the layer that doesn't cross over.
If, at this point, you can build a nonferrous metal "can" to enclose the solenoid, that'd be great. That will help the solenoid stay solid with wax even if it gets hot enough to melt the wax.
Now, get a vat of wax to 212 F, and dip the solenoid in it. Or if you've done the can thing, that can be the vat. This will boil all moisture out of the coil windings. If possible, draw a vacuum on the vat to force all the air and steam to vacate the coil windings. You could simply release the vacuum and wax should be driven into the voids left by the vacuum; however if you can pressurize the vat, that will help.
Let it slowly cool down to let the wax freeze.
Congratulations, you have just done VPI (Vacuum Pressure Impregnation) in 1019 A.D.
Now the tricky part, remelt the wax just enough to get the part free of the wax, but not so much as to melt the wax out of the windings, which would undo our work! This is where that metal can would come in handy.
Now, you should have done all this stuff with epoxy instead of wax, but you didn't want to bring any epoxy. "It's just a day trip" you said.
Now, if you need objects insulated, get maple wood. It has the best insulating characteristics of any reasonably available wood. Mill the maple down to rough dimensions, and then stick it in the wax boil for a day or two. A vacuum cycle or two wouldn't go unappreciated. You are boiling all the moisture out of the maple and replacing it with wax.
Same deal with letting it fully cool then reheating it just enough to get the wood out of the wax.
This will cause dimensional changes in the wood, which is why we waxed it "rough" before we did our woodwork. Now, have your woodcarvers do their thing. Finally, give it one more night's boil-and-freeze to make sure wax fully penetrates all the freshly exposed wood surfaces.