Probably this wont be what you want to hear, however, someone needs to get off their arse and make a start.
As always I will mention what I use, however, they are necessarily not in the frugal range and the best option.
I used to use the Leigh FMT for over 15 years and has served me well. It can do many variety of tenons,
and of course the appropriate mortices.
If you plan to do a lot of M&T joints in the future, it's hard to go past a Domino.... and don't say you don't plan to. The problem might the weigh of the decision between the 500 and the XL. Because I had the Leigh FMT, their D4R and a biscuit joiner, I could not justify the Domino for 13 years. however, once Fe$tool released their breakdown hardware for the 500, it might be a puerile justification for me, but justification it was.
In my opinion, I will confess that the Leigh FMT will do a more "accurate" set of M&T joins than the Domino... but that is based on preciseness. The Domino will place 1 (the first) accurate mortice for alignment, followed by a string of loose mortices for glue ups. The Leigh (if accurately marked) is designed for exactness.
Another option is a mortise attachment for DP,
and there are many thousands of woodworkers still "using" them and will not hesitate to recommend them.... just remember that most are seasoned woodies with years of experience behind them and too bloody pigheaded to upgrade. I bought a set, did a test run and it is stored in it's original box somewhere. Now maybe I needed to hone it, customise it, or whatever... but to me it was a bucket of shit... and I still cuss the ex-"friend" that recommended it.
Woodpeckers Morty is another option... all the recomendations I know of are based on their videos.
I'm sure there are many more "jigs" out there, but I have my bases covered by the above, so I don't need to look any further... however, someone may introduce something new that I'm not aware of that I may want to evaluate.
If your first cut is too short... Take the second cut from the longer end... LBD
