Scarlets wing Stoddart missed out on initial selection for the trip due to an injury of his own (thigh strain), but has since reached a stage in his rehabilitation which would benefit from some of the unique training conditions available on the camp.
Tovey will return home to Wales for tests to a nerve problem in his back.
“Jason has a nerve problem affecting his back, he will undergo further investigation and a scan back in Wales and we will know more once we have seen the results,” said Prav Mathema, WRU National Medical Performance Manager.
“Morgan is doing well and is now up and running again, so his rehabilitation can be improved with use of the cryotherapy chambers here in Poland.
“It therefore makes sense for him to fly out in place of Jason.”