I currently have st205/75d14 and need two additional tires for a trip this weekend. ? is can it take two tires off my other boat trailer st205/75r14 using one of each in each side? radial/bias|radial/bias or is this a no no and I should wait for the new tires on order?

Do the tires have weight ratings on them? Trailer tires usually do. If your within the weight limits, you should be just fine.