Nice set of upgrades you have going there. I have the same 238ML and love it!
and have done the following:
Upgrades I have done:
1. dual 6 volt sealed AGM's relocated to the compartment under the dining bench seat
2. additional propane outlet at front of trailer
3. BBQ mount on the front of the trailer
4. stainless steel no-flair up grill, this thing smokes a lot so mounting on the front works great as the smoke goes up not in the windows and doors.
5. hard start capacitor on AC
6. 12 USB and 2 outlet 12 volt plug outlet in cubby next to radio
7. outside LED flood light
8. folding shower door, keeps that silly curtain off you!
9. rear tow hitch for hauling bike carrier
10 custom spare tire carrier welded to tow hitch bracket so tire rides in the center between the bike carrier and the back of trailer
11. oxygenics shower head
Upgrades Planned / hoped for!
1. setup for XM radio, i like your set up
2. water collector tank, cut down on the pump running
3. replace selected interior lights with led bulbs
4. power air vent upgrade
5. bedside usb chargers to charge those mobile phone devices
6. sewer hose holder
7. replace window blinds with the pull down shades
I guess I should post some photos