Two things to consider......depth that the current speaker takes up.....this is easy to match up with Crutchfield website. Find out what the "RMS" of the gear you're using is now......it's more important to match RMS than to worry about watts of the newer speakers and watt output of the current setup.
I went with 6.5" Kicker Marine speakers to upgrade my exterior ones. They also have LED lights in them that I tied into my step lighting on the RV. KICKER | KM654 LED Coaxial
Sound is MUCH improved and were a direct swap other than connecting the power for the LED's.
I've had the Boom for a couple of years. Great little bluetooth speaker. Use inside/outside or buy 2 and couple them together for either L/R stereo or duplication of sound (1 outside/1 inside). The iRV unit and speakers are a joke...and mine is a 2016 TT.
I added a Vizio sound bar with wireless subwoofer to the inside of our PDEK and wow what a difference. 10 minute install and fit perfect. Hid the subwoofer behind the recliner.
I replaced the speakers in our Surveyor and added two in the "master bedroom". I am on my phone and don't know to post a link. If you are interested you can find the thread in the Surveyor sub forum.