basement bath drain/ venting layout

hello all, I have been looking at this forum for awhile and there is tons of great advice.
My question is regarding venting my shower and jacuzzi in a basement bath remodel. I will be removing an old toilet and using that pipe (3")to drain a shower and a jacuzzi tub. The toilet was vented through the sink drain (horizontal wet vented i think??) and i am hoping to be able to use the existing vent for the 2 new drains. My concern is the length of run for my new 2" drain lines before i get to the vent. The Jacuzzi drain pipe will run horizontal for 3ft, then 1ft vertical drop, then 1ft horizontal before the vent. The shower will run for 2ft at 45 degree slope and the 1ft horizontal before the vent.
I have attached a picture of the existing pipes and also a sketch of my plans. i have not showed any of the traps but the new drains will all have traps.

I am relatively new to this so please let me know if more information is required.
Thanks.

vent

Neither the tub OR shower drains can "drop" ANY DISTANCE before the vent. You MUST vent them prior to the drop in elevation. You also cannot tie the two of them together before the vent.

thanks hj for the info. Now that you point out those things i can see why it wouldn't work.
Any suggestions on the easiest way to vent these drains?

other options

i have a couple of other ideas here. These options will eliminate the 'drop' in elevation of the drains prior to venting.

the one option will use the wet vent from the sink to drain and vent the tub. The shower will have its own new vent added.

The other option is to drain both the shower and the tub through the wet vent.

Will either of these work? is one option better than the other?

vent

Actually, the way you have them drawn, I do not see any difference between them.

A vent rises 6" above the flood level before it can tie into the next vent. That prevents waste from submerging the vent.
Find a wall that you can run the vent(s) up.

Thanks for the replies...sorry the last two pictures were of the same layout using the wet vent for both fixtures( one aerial view and one showing the cross section--vertical). In these drawings i have lowered the traps at each drain and i have also tied into the wet vent above the 3 inch pipe(using a double wye probably), this will allow me to run the drain horizontal (less than 4 ft long@ 1/4" per ft). Since the horizontal runs will be drains (wet) it will allow the drains to be cleared by the shower/tub water if they get plugged by a backup.
Can i drain the shower and tub through the wet vent from the sink (3 fixtures total)? If it is possible should i use a double wye that is 3x3x3x3 instead of 2x2x2x2 to tie int o the 3inch pipe?
If i have to, i will run new vent lines but it will not be easy nor pretty so i am trying to see if there are other options.
Thanks again for all the help.

here are two more drawings that show the same design (more clearly i hope). the one sketch showing the cross section of the floor has 2 different views so that the angles can be seen.
Is there a concern with dropping the drains (7-8") before the traps so that they can have 1/4" slope after the trap?
Is there concern with wet venting through a double 3" wye?
thanks again for all the professional advice!!!