I totally agree with you on all points. Increasing the temperature only increases the maximum water content the air can hold (so may give you some more headroom if the ambient is near 100% RH), and improves the movement of the water molecules as the both the water and polymer molecules are more mobile. Increasing the temperature does not decrease the concentration of water molecules in the air, you can not make mass (water) disappear into nothing.

As to a personal vacuum oven, I use a large approx 4mm thick aluminium soup kettle (hotel kitchen size) with a 1" thick sheet of perspex on top. I have milled a 3mm deep round depression in the perspex sheet and poured a high temperature, high rigidity silicone rubber into it as sealing gasket. In the center of the perspex sheet I drilled and tapped entries for the manometer and ball-valves. I put a silicone heating ribbon around the kettle (stuck it in place with kapton tape) which I drive with a cheap chinese PID controller/thermistor. Around that a layer of 10cm thick glass wool. I have used a double diaphragm pump in the past, but now use a dual-stage rotary vane pump. The latter brings the pressure down to near total vacuum. I was surprised however at how hot the pumping end became, but seems to be the modus operandi of this type of pump. You will also need some good high temperature vacuum grease (laboratory supplies) to seal between the silicone and the rim of the aluminium kettle. Without it you will not get lower than 50-100 mbar in my setup due to residual leakage. I don't have a timer yet, but that should be easy to rig up.