Howdy Cat. I agree with Tad and Bill on all accounts. I was going to say that you would go threw a few 2 smoker engines in that time, but in a pinch, much easier to peddle then a 4 smoke if you do get into trouble far from home/work.
Given your states laws and requirements, have you thought of a rack mount? You can get many different higher end engines that will serve you well. Folks will say center of gravity and cargo. But they ride surprisingly well. The sound and fumes are behind you and down wind. For store runs or cargo, can use saddle bags, front basket and/or back pack.
They are pricey but will last ya. Just a thought. Lots of folks look at em and just say nope. lol.
I really like the sound of the 35s. When they go past you, makes a pleasant sort of hum. Results Page
But best advice I could give ya is ask folks near ya if you can ask questions and maybe try what your most interested in. motorized bicycle folks are really amazingly friendly and enjoy talking about their babies.
What ya gonna do in the winter?