Just changed out the ones on my RV (Bargman brand fixtures with the corresponding LED bulbs from Superbright LED. Painless changeover, in fact, I did all the clearance and marker lights as well.
On the turn signals, the flasher rate won't be impacted, so long as you leave one set of bulbs, incandescent. In my case I left my pickup truck tail lights conventional and changed everything else.
Just changed the headlight bulbs (high-low combination Halogen), to LED hi-low bulbs. Much less current draw, very bright light output.