@Dave E.,
Generally speaking, I don't worry about it that much. We use them when we buy all the time. The lenders we use for our own purchases (private lenders) trust us and they don't worry either. Unfortunately, sometimes my underlying lenders don't like it when it's someone else's loan I'm using their money to fund. If it's national lender I'm brokering for, it's another it depends. It's a very misunderstood entity and makes people who don't understand them nervous.
In our area, I've yet to find an attorney or title company that knows what to do with them. Any time an attorney or title company starts balking, lenders get nervous. We try really hard to work with the same local title companies. We've trained them on how to deal with them.
Even as a lender, there are many things I still don't understand in this industry. There are lots of inconsistencies between lenders and brokers. There's pro's and con's to it all. The biggest pro is that there's a loan program out there for just about every situation imaginable; the biggest con is trying to find it when you're deal isn't the standard run of the mill deal.
What @George Skidis said above is correct. Regardless of what your reasoning for doing something is, you need to be transparent with your lender. Even when things are allowed, when they happen after closing and the lender wasn't informed this would be happening, they feel like someone is trying to pull a fast one. It never ends well when your financial partner in the deal starts to doubt your intentions. Whether or not it's intended, the perception of deception is a relationship killer.
As for whether or not it trips the due on sale clause, it depends on what's really going on. If the lender can't tell and the borrower is being evasive (even if it's for what the borrower perceives is a good reason), the lender may call it due. Most borrowers don't realize this, but almost every commercial type loan out there (all investment loans, even from private individuals) are commercial in nature. Almost every good commercial loan paperwork has a call provision. It trumps the du on sale clause. The call provision allows a lender to call the loan due at any time for any reason without just cause. Now, no one uses this clause unless they feel threatened in the deal, but it's there. The call provision is the one that people should be more worried about than the due on sale clause.
Residential mortgages that investors take over sub-to are more likely to trip a due on sale clause. residential mortgages don't have a call provision. Because of consumer protection laws, it's not allowed. Using trusts in deceptive ways can absolutely cause the bank to use it and call the note due. More often than not, as long as things look clean and the payments are being made, the banks will leave it alone.
Most guru's teach you to use land trusts in fraudulent ways (actually, I don't know of any that don't teach this way). The only time a property is allowed to be put into a trust and not be in violation of the due on sale clause is if it it's for estate planning purposes. Putting it in a trust to hide the sale from the bank is NOT estate planning. It is potentially mortgage fraud. I haven't heard of anyone going to jail over this, but I believe that at some point someone will.
Now with all that said... Investing is a great tool to better your life with. It can be extremely profitable and ti can be extremely rewarding to help sellers out of tough spots. Learn what you can so that you run a clean business. But get out there are do business. Go help some people and make some money.
Good luck!