It would be difficult, but it's not impossible. There are specific challenges, but all of them can be overcome--And once done, it actually has the potential to sound better than most high end home systems precisely because it is a closed environment.
Specific to this type of application, other than the 'usual' things already mentioned, the keys are:
1. Mounting speakers in a front firing position rather than straight down. Or better yet, permanently mount high quality small bookshelf speakers (I did this in the bedroom on the nightstands--they can act as a stable stand if done right)
2. Use of a DSP processor---current high end is something like Audison (it equalizes for the environment and adjusts for your specific speaker type---It makes a HUGE difference once it's dialed in) The signal is taken from the head unit, processed and then sent to your amplifier for output to your speakers.
3. Upgrading the subwoofer to a high end powered compact home version (something like a compact REL, that can be integrated with the other speakers) This will, however require shore/generator power.
4. Strategic sound deadening with window coverings, etc.
5. Use of non-compressed music
Set it up right and you can have a whole different type of relaxation experience camping (I actually sometimes enjoy it more than my home system---like you, I have a high end home system). You will also be very popular tailgating.
You will probably still have the problem of your wife making you turn it down!