If you need a real workhorse for inland and coastal use, you want a Dory. Trouble is of course they aren't inflatable, but are no worse than a RIB for portability. Weight varies hugely with hull material, there are some that are very light indeed. You may want to look up ex mil boats, although the ones I've used were in pretty poor nick and also heavy. Advantage was power, reliability and price. Many Dories claim to be used by the military - so many I wouldn't believe half of it, but they are used for inland and shore work by the military because that is the best hull shape.
A planing hull is fine if you are going a bit farther, and will cope excellently with waves, but are more of a fiddle to land. PM me if you want more info, I've been teaching from the sort of craft you mean for 5 years so I've a fair bit of experience
MEN WANTED FOR HAZARDOUS JOURNEY. SMALL WAGES, BITTER COLD, LONG MONTHS OF COMPLETE DARKNESS, CONSTANT DANGER, SAFE RETURN DOUBTFUL. HONOR AND RECOGNITION IN CASE OF SUCCESS.
Reverend "Norwegian Spruce" Arctic Hobo of the Bushcrafti