Does the PAL take longer to acquire than the RPAL?
If you have no intention of purchasing a firearm at all while in Canada & (as I've read so far) only want your shotgun with you, I'd save time/money/extra scrutiny/background checks and just get the PAL not RPAL.
If you make friends with someone while here and they have an RPAL and you want to go to the range and use their firearm, range rules, provincial laws permitting - you're OK to do that. Your call of course. Just based on what I've read here it doesn't seem like its worth your time for the extra work for the RPAL. - Different story if you intend to move here permanently or want to purchase restricted.