Thanks for taking the time to put these posts together. I'm in pretty much the same selling position and for similar reasons, looking at Merry Fisher, Quicksilver or similar.
I suggest a 70lb Watersnake with 100Ah Lithium would do the job nicely to drive any size tender. I use it as an aux on my 4.55m open console boat and it drives it very well (with passengers) without breaking the bank. £270 for motor (ebay), £70 for battery box (ebay) and £280 for the battery...
Prerequisite is to optimise engine height or else the final pitch choice may be different or even no change be needed!
Start with the AV plate 1 hole (20mm) above level with keel and if it doesn't ventilate raise it another hole or lower it if it does.
If it's fixed trim those holes are...