They are out there. Both RJ85's and BA-146....same plane but different engines and both have been converted to tankers.
But again you're talking a 1990-2001 airframe which is already 25 years out of date and no longer manufactured. The only reason they're viewed as "new" is that they're replacing the older Convair 240/340/540 series that have been recently retired. Saskatchewan up until recently had a Convair 240 tanker that used to be a VIP transport under the Eisenhaueser administration (replaced by Dash8-Q400).
The only reason the older L-188 Electra's are still flying is that the company replaced almost every part on every wing with brand new custom made parts. The only reason they're viewed as "new" is that they're replacing the older Convair 240/340/540 series that have been recently retired.
CL-215's are old now. And wore out unless major overhaul/rebuilds done. But that's a 1966-1987 airframe.
CL-415's were built 1993-2015. And are starting to get replaced via the orders for the new CL-515
Conair has the contract for the Bombardiar Dash 8-Q400's, AT-802's, and AT-802U's in Alberta and provides the pilots/support via contract for the Saskatchewan new Dash-8 Q400.planes. Manitoba only runs CL-415's but not sure what the pilot/support situation is. Conair also has a long history of working with via aircraft/support for Securitie Civile in France:
Sécurité Civile - Wikipedia which is where the Dash-8 conversion was developed and first used.
AirSpray also provides tankers to mulitiple western Canadian provinces but a more limited fleet than Conair.
The big message here is the parts and support services are getting harder and harder to source. Rules are stricter of part sourcing, the older miliary boneyards are no longer acceptable sources to raid, and many airframes have been used hard for too many years and now need a full structural rebuild or replacement. All of which is moving to more and more modern frames instead of cheap, limited part source, historical frames.