I can't think of any issues besides installing stronger struts to support the extra weight for the under bed access.
If you haven't already , you may want to consider a foam mattress , trimming a king size foam mattress to the size you want could be a much cheaper alternative, to fitting in a coil spring mattress, and with considerably less movement transfer, from partner to partner, if one or both are restless sleepers.
I'm currently on foam , in both home and RV.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.