In the Parc Eirias sunshine, Wales crossed for a total of 14 tries as Ellis Jenkins, Alex Cuthbert and Thomas Young all added braces and fly-half Gareth Anscombe kicked a 14-point haul.
Anscombe also crossed for a try of his own, as did his captain Jamie Roberts, in a convincing victory which also saw RGC score through Afon Bagshaw, Tom Hughes and Evan Yardley.
Against a tough-tackling RGC outfit, Wales ran riot in the opening quarter to move 33-0 up.
Allen and Jenkins both crossed twice, the Cardiff Blues duo finding space in the wide channels and making the most of their opportunities to score.
Allen’s first was the pick of the tries, the centre, who was playing on the wing, chipping through and collecting his own kick to score. Morgan then added Wales’ fifth try, smashing through two home tackles to make his way over the line.
Anscombe added four of the five conversions, and although Bagshaw gave the Eirias crowd something to cheer about with RGC’s first try, Robin McBryde’s men continued to impress as they ramped up their preparations ahead of facing the Pacific Islanders later this month.
Sam Davies’ break allowed Morgan to add his first, Anscombe kicking the extras, before Wales skipper Roberts was both villain and hero within the space of a few minutes.
First, the centre’s pass was intercepted by Hughes, who waltzed over to score. Then, Roberts responded with a try of his own, benefiting from a trademark powerful carry.
Jacob Botica and Anscombe kicked both conversions, and there was still time for two more scores before the break with Yardley and Morgan both crossing for converted tries.
Wales had already made a series of changes before the break, including replacing their entire front row, but the scoring continued as some fresh faces made an immediate impression.
Just minutes after coming on at half time, Cuthbert collected an Anscombe chip and dived over and the creator then turned scorer as the fly-half sprinted clear for an impressive solo effort.
Young was the next man on the scoresheet for his first Wales try, the Wasps flanker sniping over from the side of a scrum, but all three conversions went wide with Owen Williams off target with two of them.
It took the score to 69-19 and although the result was done and dusted, RGC kept going.
The WRU National Cup champions refused to give in, and after Allen sealed his treble of tries, Wales’ replacement scrum-half Tomos Williams was yellow carded.
His 10 minutes in the bin was evidence of RGC’s endeavour, but it failed to stop Young and Cuthbert from completing the scoring as an entertaining encounter drew to a close.
