I love your enthusiasm and dreams. Quite honestly, I often think the same way. I think, hey, I can go everywhere on my bike, who needs a car? Answer ... My wife.

Needless to say, there is no way my wife can go 50 miles on her own, yet we have successfully done an 89 mile day on our triplet tandem, followed by another 60 miles the next day. I would argue that given the right equipment (a decent bike, food, tools, etc.) the primary predictor would be motivation. If your wife is like "Yeah, lets go for it," then do it. It will be an adventure for the two of you. On the other hand, if she thinks more like "I don't know, this is not going to be fun," then I would certainly think again. Do remember you will have to ride back the same distance. Also consider the wind. Perhaps consider going the full distance but also have a back up plan. I would argue that trying something once is not a bad idea. I would do lots of training but then decide on a time and do it. If its too hard, its not like you've made a commitment to do 150/day every weekend.

By the way, you mention going by way of the Katy Trail. I live in Kansas City and it sounds like you might be traveling either to or from KC. If this is the case, I would be happy to ride with you or possibly give you a ride part way or something.

As mentioned earlier, you could also easily camp half way. While there isn't any camping actually on the trail, there are a number of towns you can camp in for very low cost or free.

Most importantly, Listen and be sensitive! Good luck, and please let me know if you are in my area