DTS-HD MA and TrueHD (not DD TrueHD) are lossless data packing algorithms. Think of it as zipping a large file on your computer; you're not throwing out any of the data, just packing it more efficiently in a smaller space. That's what DTS MA and TrueHD are. Nothing more complicated than that.
As such, DTS MA and TrueHD soundtracks can be any number of channels from 1 to 7.1 (the BD spec doesn't allow for more than 8 audio channels). Since those codecs aren't fixed to a certain number of channels, you don't have to use a certain number of speakers.
Besides, modern receivers scale the number of channels in the source material to the number of speakers in your set-up. 2-channel can be upmixed to your 5 speakers and 7.1-channel material can be downmixed to your 5 speakers.
So set up as many (or few) speakers as you can accomodate, and don't worry about how many channels or which audio codec the soundtrack uses. You won't have any problems during playback.