Got to side with Flyfish Dog about the weight.
A heavy yak or canoe becomes a rarely used yak or canoe. Car top it a couple of times and you start to cringe just thinking about going fishing in it.
I use a trailor myself because I have heavy boats and light boats and that does help.
I'll give a very subjective opinion; for me, 60lbs is max on a solo boat. That being said, everyone is different.
Good luck and hope it works out whatever boat you end up with.