3/8" under 1/2" foamboard; is this ok?

[videobruce]

3/8" ply under 1/2" foamboard; is this ok?

Using 3/8" plywood with 1/2" rigid foamboard over it on a around the wall layout in N scale (34" table depth) using cookie cutter construction, is this a problem with the flexing, expansion & contraction of the plywood in a non temperature controlled basement?
Temperature varies from 55 to 75 degrees, but humidity has varied from 45 to sometimes close to 100%, but there is a dehumidifier, so high humidity will probably be 75 to 80%.

I was concerned with overall weight of the plywood and thickness of the foamboard when it comes to work with linkage of turnouts. I also have no plans to 'dig down' below the top of the foam for scenery reasons which is why I choose 1/2" over 1".

 

[Burlington Bob]

The dehumidifier in my basement will keep the humidity at 55% or less. If yours doesn't, you may need another or one with more capacity.

 

[videobruce]

It's more than enough just for the room where the RR is, but it's too noisy and the drain line would be too long if I placed it there. I don't want to have to empty out the bucket every day w/o the drain tube.

Besides that device spins my electric meter too fast.
(another power hog)

 

[Burlington Bob]

You can buy a little pump from Amazon that will pump the water from your dehumidifier to a drain pretty cheap. I use the same one for my dehumidifier that my furnace uses. I just have a three foot piece of old garden hose connected to the dehumidifier and stuck in the little sump for the pump. Works great.

 

[videobruce]

No pump is needed, just a longer drain tube that I don't want to bother width. But that doesn't solve the problem of the noise.
The unit is between the two furnaces (upper & lower flats) across from outside the door to the room in the middle of the basement. The other problem is the heat from the exhaust, raising the temperature 5 degrees in the summer in the basement.