You should combine the adjacent strata to avoid any single unit stratum. Different approaches can be used. For example you can do the following

gen strata2 = strata
replace strata2 = 4 if inrange(strata,1,3)
replace strata2 = 10 if strata == 11
replace strata2 = 19 if strata == 18
replace strata2 = 21 if strata == 20
replace strata2 = 28 if strata == 27
replace strata2 = 37 if strata == 36
replace strata2 = 45 if strata == 44
replace strata2 = 55 if inrange(strata,52,54)
replace strata2 = 64 if strata == 63
replace strata2 = 70 if strata == 71