Hi,
I live in Casper, are you sure he died in 1830? There was no Casper until 1888, before that(1861-1865) there was Platte Bridge Station, later renamed Fort Caspar, in honor of Lt. Caspar Collins d. July 1865. There was the Mormon Ferry that was near here as early as 1847.
I just went to the library and I got one of the Cemetery indexes, I looked and there are 2 Weber's in there, John P. d. 9 Dec 1964, 63 yrs and Terry d. 25 Dec 1957, 10mo.
When I go back to the library I will look at the others and see if your Alexander is in there.
Sorry I couldn't be of more help,
Kristine