We have a 2011 17B. We are old backpackers so light on the amenities is fine with us. My rule was only add that which cannot be added later. So,
* no A/C. It needs 120V and that's hard to do w/out a genset in the woods.
* Got extra insulation and double pane windows. Note that this works for both heat and cold...
* Didn't get the storage box. It can be added later if necessary.
* Oven? No. the mentioned Weber gas grill can bake/roast.
* Solar? Had the rough wiring done but ended up getting a portable 135W unit which can really be in the sun (works better...) while the trailer is in the shade.
* Dual 6V batteries. If you are running inverters, your amp-hours go quickly... The 135W solar charges them just fine.
* Got a portable inverter later, enough to charge items (laptop) that need AC power bricks.
* TV? That's why I camp. That and reception is c**p even at home. Bring your iPad/laptop/Nexus and watch netflix... In other words, dual use things.
* Got 3 burner stove, outside shower, and s/s sink. Again, can't add them later.
If it gets things hot/cold, gas is more efficient in the boonies so no dual hot water or heater. The 17B fridge is 3 way anyway. We only use AC to chill it down the night before, use DC on the road (slows battery charge), and gas in camp. We only stop at RV parks so we can dump tanks and have no other options.
The other advise (from this forum) is not to get out the tools to mod something for at least a year. Why make a mod you don't need in the end. Feel the need and then do the mod.
Hope this helps.