As an addendum to this discussion, because you now say you're "leaning towards solar but might just start with another battery" perhaps I can offer a couple of other observations ..... :W
Investing in another battery isn't a bad idea in itself, one I wouldn't particularly disagree with, even considered it myself - after all, if one G27 will get you through 3 days of camping without a recharge then two G27s would logically get you through 6 days. However, there is a catch ... it's generally accepted that one would want to not draw any 12 volt deep cycle battery down to any less than ~ 50% SOC or ~ 12 volts on a regular basis. Occasionally drawing it down a bit further is OK but make it a regular habit and you'll be replacing that battery sooner rather than later. That then brings up the question of timing your recharge, because the second generally accepted rule is that once drawn down you'd want to recharge that battery as soon as is practical, not just leave it sit for days or even weeks before you got access to shore power and could then properly recharge the battery. Solar is fine for what it is but if your system becomes ineffective because of unfavourable weather for days at a time your depleted battery is going to suffer for it. That's where a genset beats solar hands down as you're free to recharge as often as your battery needs it, and while you'd probably prefer to not run the genset so long that it can restore your battery to a full 100% getting it to a 90% SOC is easily achievable in 3 hrs or less of genset runtime. And that's where I see solar as best fitting in - allow it to do that last 10%, when it can ... if the weather doesn't cooperate, no loss, because at 90% SOC you're still good for another couple days of camping ... if the weather does cooperate and you do achieve 100% SOC then simply consider it a bonus.
