Solo'ing V2R is very do able. Is it smart? Maybe, maybe not. Its only approx 540 miles this year which is about 100 more then this years Baja 500. But the terrain & crew logistics make this race much easier IMO then a Baja race. Casey makes it where two trucks can support you the whole race. I've seen guys pitting out of a station wagon before!
Now Solo'ing a Baja 1000 in a UTV sounds impressive and courageous, but not smart in my book. Sure its the true David & Goliath story, and if finishing is your goal, then go big! If you want to win be smart and surround yourself with people who can get the team a victory.
I have yet to see in anything but maybe TT & class 1 where a solo effort has brought a better result then having a teammate. If you say "I hate to see someone throw all my hard work away" then you have just not found the right teammate. Look at it from the other side. "I hate to see arrogance in a driver throw it all away, as he is not willing to know the gains of having a real crew or support driver can offer his efforts.
You can be in great physical shape but the fact is, its the mental exhaustion that gets you. There is no way a driver who has been in the seat for 10 + hours strait can and will be as mentally focused and have the reaction time of a driver of equal skill with only 2 hours of seat time.
And I have heard the story, and reasons for keeping a tired driver in the seat. "The car is tired and he knows how far to push it." A fresh driver will run it into the ground". I say an inexperienced driver or driver not fit for your team might. But if you get someone with experience who understands the car, and the feel of the car he will adapt to the handing or lack there of, and only push it as far as the car will allow.
A teammate is not something you place a craigslist ad for or make some sort of financial deal with. Like you pay for half of the costs and you get the car for half the race. If you own a car and are looking to win, you build a team that can win. I have seen lots of guys team up due to cost, but typically they know each other, have been competitors of each others, and know each others driving styles. Like this year's 500 with Johnny & Brain teamed up. They knew each other and knew what to expect from each other. So in their case a one race teammate deal worked.