Brother, if your dehummer is set at 35 and you get to 70 at night, you definitely need another one. A properly sized dehummer makes all the difference in the world when you're fighting PM.
The LG 70 pint model should bring it down to a reasonable level in conjunction with the one you have. The reason I would get the LG over the Frigidaire, ( both commonly found at HD or Lowes) is the capability to run a constant drain to a rez, the Frigidaire doesn't have the option. As you've already found, the built in rez isn't big enough and it shuts down long before lights on. Very bad thing.
I found that out the hard way. Pretty easy to drill a hole, stab in a grommet and run a hose. Pain in the ass though.
Hope this helps,
Fred