it is highly recommended that NO one enter or exit a skid steer, or stand under the boom at all, without the boom being supported safely, using the OEM lock out, or some other SAFE Way
using 2x4's I would NOT call being safe, there wood, the boom can be very heavy or have leverage which can make it seem even heavier
I also, highly recommend you remove the bucket or any implement if you do lift boom up and lock it in the up position
as this will be safer by removing some weight to things,
but again it is NOT recommend to exit(or enter) a skid steer with boom up, unless boom is locked in the up position
lots of folks have been killed or seriously hurt over the yrs, when a boom came down on them
once in the ,locked position, someone can get in and out of machine, start and stop and run things,
BUT they cannot lower boom without unlocking it, and again MUST re lock things to get back out safely!